Final Revision Checklist for IGCSE WJEC Computer Science | IGCSE WJEC 计算机：期末复习提纲

📚 Final Revision Checklist for IGCSE WJEC Computer Science | IGCSE WJEC 计算机：期末复习提纲

This article provides a structured revision checklist covering all key topics in the IGCSE WJEC Computer Science syllabus. Use it to review definitions, recall concepts, and practise exam-style questions. By working through each section, you can identify strengths and close gaps before the final exam.

本文提供了一份结构化的复习清单，涵盖了 IGCSE WJEC 计算机科学大纲中的所有关键主题。你可以用它来回顾定义、回忆概念并练习考试式题目。通过逐一完成每个部分，你能够找出自己的强项并在期末考试前弥补薄弱环节。

1. Data Representation | 数据表示

Understanding how computers represent numbers, text, images and sound is fundamental. The binary system uses only 0 and 1, which matches the on/off states of digital circuits. Calculating file sizes and converting between binary, denary and hexadecimal are common exam skills.

理解计算机如何表示数字、文字、图像和声音是基础。二进制系统只使用 0 和 1，这正好对应数字电路的通断状态。计算文件大小以及在二进制、十进制和十六进制之间进行转换是常见的应试技能。

Binary and denary conversion: Be able to convert between binary and denary for integers up to 16 bits, and denary to binary using the division-by-2 method.
二进制与十进制转换： 能够对至多 16 位的整数进行二进制与十进制互转，并使用除 2 取余法将十进制转为二进制。
Hexadecimal: Understand why hex is used (shorter representation, easier to read) and convert between hex, binary and denary.
十六进制： 理解使用十六进制的原因（更短小的表示，更易读），并能进行十六进制、二进制和十进制之间的转换。
Binary addition and overflow: Add two binary numbers, detect overflow when the result exceeds the bit width, and explain the consequences.
二进制加法与溢出： 完成两个二进制数的加法，当结果超出位宽时能够检测出溢出，并解释其后果。
Units of storage: bit, nibble, byte, kilobyte (KB), megabyte (MB), gigabyte (GB), terabyte (TB) — know the size relationships (powers of 2) and typical file sizes.
存储单位： 位、半字节、字节、千字节（KB）、兆字节（MB）、吉字节（GB）、太字节（TB）——掌握它们之间基于 2 的幂次的大小关系与典型文件大小。
Character sets: ASCII (7-bit, 128 characters) and Unicode (multi-byte, supports global characters). Compare their storage needs and limitations.
字符集： ASCII（7 位，128 个字符）和 Unicode（多字节，支持全球字符）。比较它们的存储需求与局限性。
Images: Explain bitmaps as grids of pixels storing colour values; calculate file size from resolution and colour depth; describe how increasing resolution or colour depth affects quality and storage.
图像： 将位图解释为存储颜色值的像素网格；根据分辨率和颜色位深计算文件大小；描述提高分辨率或颜色位深如何影响画质与存储量。
Sound: Understand sampling (sample rate, bit depth, duration) and calculate file size of an uncompressed sound file. Explain how higher sample rate and bit depth improve quality but increase file size.
声音： 理解采样（采样率、位深、时长）并计算未压缩音频文件的文件大小；解释为何较高的采样率和位深能提升音质但会增加文件大小。
Compression: Distinguish between lossy and lossless compression with examples (JPEG, MP3 for lossy; ZIP, PNG for lossless), and evaluate their use for different data types.
压缩： 区分有损压缩和无损压缩并举例（JPEG、MP3 为有损；ZIP、PNG 为无损），评估它们在不同数据类型中的适用性。

2. Hardware | 硬件

Hardware refers to the physical components of a computer system. In the exam, you need to describe the function of the CPU, memory types, input/output devices, and secondary storage. The Von Neumann architecture is central to understanding how a processor fetches and executes instructions.

硬件是指计算机系统的物理组件。在考试中，你需要描述 CPU 的功能、存储器类型、输入/输出设备以及辅助存储器。冯·诺依曼体系结构是理解处理器如何取指和执行指令的核心。

CPU components: Control Unit (CU) – directs operations; Arithmetic Logic Unit (ALU) – performs calculations and logic; registers (PC, MAR, MDR, ACC) – temporary storage inside the CPU.
CPU 组成部分： 控制单元（CU）——指挥操作；算术逻辑单元（ALU）——执行计算与逻辑操作；寄存器（PC、MAR、MDR、ACC）——CPU 内部的临时存储器。
Fetch-Decode-Execute cycle: Describe each stage: PC → MAR → memory read → MDR → IR → decode → execute (using ALU if needed) → store result.
取指-译码-执行周期： 描述每个阶段：PC→MAR→读取内存→MDR→IR→译码→执行（若需要则使用 ALU）→存储结果。
Factors affecting CPU performance: Clock speed, number of cores, cache size. Explain how each influences speed but also note that increasing cores does not give a linear speed-up due to software limitations.
影响 CPU 性能的因素： 时钟频率、核心数量、缓存大小。解释它们各自如何影响速度，但也要指出由于软件限制，增加核心数量并不会带来线性加速。
Embedded systems: A dedicated computer system within a larger device (e.g. washing machine, car engine management). Characteristics: low power, specific task, real-time response.
嵌入式系统： 嵌入在较大设备中的专用计算机系统（如洗衣机、汽车发动机管理系统）。特点：低功耗、特定任务、实时响应。
Memory hierarchy: Registers (fastest, smallest) → cache → RAM → secondary storage (slowest, largest). Explain why cache improves performance by holding frequently used instructions and data.
存储层次： 寄存器（最快、最小）→缓存→RAM→辅助存储器（最慢、最大）。解释为何缓存通过保存常用指令和数据来提升性能。
RAM vs ROM: RAM is volatile, holds running programs and data; ROM is non-volatile, stores boot instructions (BIOS).
RAM 与 ROM： RAM 是易失性的，存放运行中的程序和数据；ROM 是非易失性的，存储启动指令（BIOS）。
Secondary storage: Magnetic (HDD – large capacity, mechanical), solid-state (SSD – fast, no moving parts, more expensive per GB), optical (CD/DVD – portable, low capacity). Choose suitable storage for given scenarios.
辅助存储器： 磁介质（HDD——容量大、机械式）；固态（SSD——速度快、无运动部件、每 GB 成本较高）；光介质（CD/DVD——便携、容量低）。为给定场景选择合适的存储设备。
Input and output devices: For a range of devices (e.g. barcode reader, touchscreen, speakers, 3D printer), describe their purpose and how they are used in real-world applications.
输入与输出设备： 针对一系列设备（如条码读取器、触摸屏、扬声器、3D 打印机），描述其用途及在现实应用中的使用方式。

3. Software | 软件

Software includes the programs that run on a computer. Distinguishing between system software and application software is a key learning outcome. Operating systems, utilities, and language translators all fall under system software and have distinct roles.

软件包括在计算机上运行的程序。区分系统软件和应用软件是一个关键的学习成果。操作系统、实用工具和语言翻译器都属于系统软件，并具有各自不同的分工。

System software vs application software: System software manages hardware and provides a platform for applications (OS, utilities, translators). Application software performs user-oriented tasks (word processor, web browser, game).
系统软件与应用软件： 系统软件管理硬件并为应用程序提供平台（操作系统、实用工具、翻译器）。应用软件执行面向用户的任务（文字处理器、网页浏览器、游戏）。
Operating system functions: Memory management, multitasking, file management, peripheral management, user interface, security (user accounts, access rights).
操作系统功能： 内存管理、多任务处理、文件管理、外设管理、用户界面、安全（用户账户、访问权限）。
Utility software: Antivirus, backup, disk defragmentation, compression tools, encryption software. Know the purpose of each.
实用工具软件： 防病毒、备份、磁盘碎片整理、压缩工具、加密软件。了解每个工具的目的。
Translators: Compiler – translates high-level source code into machine code all at once (produces executable file). Interpreter – translates and executes line by line. Assembler – converts assembly language to machine code.
翻译器： 编译器——一次性将高级源代码翻译为机器代码（生成可执行文件）。解释器——逐行翻译并执行。汇编器——将汇编语言转换为机器代码。
Ethical and legal considerations of software: Copyright, licensing (proprietary, open source, freeware, shareware) and the importance of respecting intellectual property.
软件的伦理与法律考量： 版权、许可方式（专有软件、开源软件、免费软件、共享软件）以及尊重知识产权的重要性。

4. Networks | 网络

Computer networks enable devices to share data and resources. For the exam you should be able to define types of networks, describe common topologies and hardware, and explain how data is transmitted using protocols. The layered TCP/IP model provides a framework for understanding internet communication.

计算机网络使设备能够共享数据和资源。在考试中，你需要定义网络类型，描述常见的拓扑结构与硬件，并解释如何使用协议传输数据。分层的 TCP/IP 模型为理解互联网通信提供了框架。

LAN vs WAN: LAN covers a small geographical area (school, office), usually owned by one organisation. WAN covers a large area (internet, connecting cities), uses third-party communication links.
LAN 与 WAN： LAN 覆盖较小地理区域（学校、办公室），通常由一个组织拥有。WAN 覆盖广大区域（互联网，连接城市），使用第三方通信链路。
Network hardware: Switch (connects devices within a LAN, intelligent forwarding), router (connects different networks, directs packets), NIC (network interface card), modem (converts digital/analogue signals).
网络硬件： 交换机（在 LAN 内连接设备，智能转发）、路由器（连接不同网络，导向数据包）、网卡（网络接口卡）、调制解调器（转换数字/模拟信号）。
Network topologies: Star (all devices connected to a central switch; failure of one cable affects one device; easy to add/remove) and mesh (each device connected to several others; robust but expensive).
网络拓扑： 星形（所有设备连接到中央交换机；单根电缆故障只影响一台设备；易于增删）和网状（每台设备与其他多台相连；健壮但昂贵）。
IP addressing and MAC addresses: IP address (logical, can change, used for routing) vs MAC address (physical, unique to NIC, used within local network).
IP 地址与 MAC 地址： IP 地址（逻辑地址，可变，用于路由）与 MAC 地址（物理地址，网卡唯一，用于局域网内）。
Protocols: HTTP/HTTPS – web pages; FTP – file transfers; SMTP – sending email; POP3/IMAP – receiving email; TCP – reliable packet delivery; IP – routing packets. Know the purpose of each.
协议： HTTP/HTTPS——网页；FTP——文件传输；SMTP——发送邮件；POP3/IMAP——接收邮件；TCP——可靠的数据包投递；IP——路由数据包。了解每种协议的目的。
The four-layer TCP/IP model: Application (HTTP, FTP, SMTP), Transport (TCP), Internet (IP), Link (Ethernet, Wi-Fi). Be able to explain how data passes through the layers when a web page is requested.
四层 TCP/IP 模型： 应用层（HTTP、FTP、SMTP）、传输层（TCP）、互联网层（IP）、链路层（以太网、Wi-Fi）。能够解释请求网页时数据如何在各层之间传递。
Encryption and network security: Symmetric vs asymmetric encryption; use of SSL/TLS for secure web transactions (HTTPS). Firewall and MAC address filtering as security measures.
加密与网络安全： 对称加密与非对称加密；使用 SSL/TLS 实现安全 Web 事务（HTTPS）。防火墙和 MAC 地址过滤作为安全措施。

5. Cyber Security and Threats | 网络安全与威胁

As networks become more widespread, understanding security risks and prevention methods is essential. The syllabus includes common attack methods and both technical and human-centred protections. Strong policies and user awareness are as important as technology.

随着网络的普及，了解安全风险和防范方法至关重要。大纲涵盖了常见的攻击方法以及技术层面和以人为中心的防护措施。健全的策略和用户意识与技术同样重要。

Malware: Virus (attaches to files, spreads via human action), worm (self-replicates across networks), Trojan horse (disguised as legitimate software), ransomware (encrypts files, demands payment), spyware (covertly monitors activity).
恶意软件： 病毒（附着于文件，通过人为操作传播）、蠕虫（在网络上自我复制）、特洛伊木马（伪装成合法软件）、勒索软件（加密文件、索要赎金）、间谍软件（暗中监视活动）。
Social engineering: Phishing (emails pretending to be from trusted sources), blagging (inventing a scenario to gain info), shouldering (looking over someone’s shoulder). Focus on the human weakness exploited.
社会工程学： 网络钓鱼（冒充可信来源的邮件）、欺诈（编造情景以获取信息）、肩窥（越过他人肩膀偷看）。重点是利用了人性的弱点。
Denial of Service (DoS) attacks: Flooding a server with traffic to make it unavailable. A DDoS uses multiple compromised computers (botnet).
拒绝服务攻击（DoS）： 用大量流量淹没服务器使其不可用。分布式拒绝服务（DDoS）利用多台受感染计算机（僵尸网络）。
Protection measures: Firewalls (filter incoming/outgoing traffic), anti-malware software, regular updates and patches, strong passwords, two-factor authentication, user training, access rights, penetration testing.
防护措施： 防火墙（过滤进出流量）、反恶意软件、定期更新和补丁、强密码、双因素认证、用户培训、访问权限、渗透测试。
Vulnerabilities: Unpatched software, weak default passwords, misconfigured systems, removable media. Explain how each creates a security risk.
漏洞： 未打补丁的软件、脆弱的默认密码、配置不当的系统、可移动介质。解释它们各自如何造成安全风险。

6. Algorithms and Problem Solving | 算法与问题求解

Algorithmic thinking is the core of computational problem solving. You must be able to design, trace and compare algorithms using pseudocode or flowcharts. Standard searching and sorting algorithms are specifically required. Efficiency analysis using simple comparisons is also expected.

算法思维是计算问题求解的核心。你必须能够使用伪代码或流程图设计、追踪和比较算法。大纲明确要求掌握标准的查找和排序算法。还会考察使用简单比较来分析效率。

Algorithm representation: Pseudocode (written in English-like statements with consistent syntax) and flowcharts (standard symbols for start/end, process, decision, input/output).
算法表示： 伪代码（用类英语语句编写，保持一致的语法）和流程图（起止框、处理框、判断框、输入输出框等标准符号）。
Sequence, selection, iteration: Identify these constructs in algorithms. Selection uses IF…THEN…ELSE; iteration uses FOR (count-controlled), WHILE and REPEAT…UNTIL (condition-controlled).
顺序、选择、迭代： 识别算法中的这些结构。选择使用 IF…THEN…ELSE；迭代使用 FOR（计数控制）、WHILE 和 REPEAT…UNTIL（条件控制）。
Linear search: Check each element in turn until the target is found or the list ends. Time complexity: O(n). Useful on unsorted data.
线性查找： 依次检查每个元素，直到找到目标或列表结束。时间复杂度：O(n)。适用于未排序的数据。
Binary search: Repeatedly divide a sorted list in half, discarding the half that cannot contain the target. Time complexity: O(log n). Explain why the list must be sorted.
二分查找： 反复将有序列表分成两半，丢弃不可能包含目标的那一半。时间复杂度：O(log n)。解释为什么列表必须有序。
Bubble sort: Compare adjacent pairs and swap if in wrong order; repeat passes until no swaps. Time complexity O(n²). Trace a given list through the algorithm.
冒泡排序： 比较相邻元素，若顺序错误则交换；重复遍历直到无交换发生。时间复杂度 O(n²)。能够追踪给定列表在该算法中的变化过程。
Merge sort: Divide the list into single elements, then merge sublists in sorted order. Time complexity O(n log n). Explain space trade-offs compared with bubble sort.
归并排序： 将列表划分为单个元素，再按排序顺序合并子列表。时间复杂度 O(n log n)。解释与冒泡排序相比在空间上的权衡。
Trace tables: Use trace tables to document variable values step-by-step, typically for a given pseudocode algorithm. Essential for identifying logic errors.
追踪表： 使用追踪表逐步记录变量的取值，通常用于给定的伪代码算法。这对识别逻辑错误至关重要。

7. Programming Concepts | 编程概念

Though the written exam does not require you to write code in a specific language, you must understand universal programming constructs. Questions often provide pseudocode or ask you to correct logic errors. Key concepts include variables, data types, string manipulation, subroutines, and basic data structures.

尽管笔试不要求你用特定语言编写代码，但你必须理解通用的编程结构。题目通常会给出伪代码或要求你纠正逻辑错误。关键概念包括变量、数据类型、字符串处理、子程序以及基本的数据结构。

Variables and constants: Variable – a named storage location whose value can change. Constant – a value that is fixed during program execution; used for readability and reducing magic numbers.
变量与常量： 变量——一个命名的存储位置，其值可以改变。常量——程序执行期间固定的值；用于增强可读性并减少魔术数字。
Data types: Integer (whole numbers), real/float (decimal numbers), Boolean (TRUE/FALSE), character (single symbol), string (sequence of characters). Select the most appropriate type for a given purpose.
数据类型： 整型（整数）、实型/浮点型（小数）、布尔型（TRUE/FALSE）、字符型（单个符号）、字符串（字符序列）。为给定目的选择最合适的类型。
String manipulation: Length, sub-string (slicing), concatenation, case conversion, character-to-ASCII conversion and vice versa.
字符串处理： 长度、子串（切片）、拼接、大小写转换、字符与 ASCII 码转换。
Arithmetic and comparison operators: +, -, *, /, MOD (remainder), DIV (integer division); ==, !=, >, <, >=, <=; AND, OR, NOT logical operators.
算术与比较运算符： +、-、*、/、MOD（取余）、DIV（整除）；==、!=、>、<、>=、<=；逻辑运算符 AND、OR、NOT。
Subroutines – functions and procedures: Procedures perform actions; functions return a single value. Know how parameters pass values (by value – a copy is passed). Understand that local variables exist only inside the subroutine.
子程序——函数与过程： 过程执行操作；函数返回单个值。了解参数如何传值（按值传递——传递副本）。理解局部变量仅存在于子程序内部。
1D and 2D arrays: Declare, index (starting from 0 or 1 depending on pseudocode convention given), traverse with loops. Apply to real-world scenarios like storing temperatures over a week or a tic-tac-toe board.
一维与二维数组： 声明、索引（根据给定的伪代码约定从 0 或 1 开始）、使用循环遍历。应用于现实场景，如存储一周内气温或井字棋棋盘。
File handling (basic): Open a file for read/write, read a line, write a line, close a file. Typical pseudocode syntax will be provided.
文件处理（基础）： 打开文件进行读/写、读取一行、写入一行、关闭文件。通常会提供典型的伪代码语法。

8. Logic and Boolean Algebra | 逻辑与布尔代数

Logic gates form the building blocks of digital circuits. You should be able to draw truth tables, recognise standard gate symbols, and combine gates into simple logic circuits. Boolean algebra can simplify expressions, reducing the number of gates needed.

逻辑门构成了数字电路的基本构件。你需要能够绘制真值表、识别标准门符号，并将多个门组合成简单的逻辑电路。布尔代数可以化简表达式，从而减少所需的门数量。

Basic gates: NOT (inverter), AND, OR. Know the truth tables and symbols (British standard rectangle symbols with notations).
基本门： 非门（反相器）、与门、或门。掌握真值表和符号（带标记的英标矩形符号）。
Combining gates: NAND (AND + NOT), NOR (OR + NOT), XOR (exclusive OR). Truth tables for each. NAND and NOR are called universal gates because any circuit can be built using only NAND (or only NOR).
组合门： 与非门（AND+NOT）、或非门（OR+NOT）、异或门（XOR）。各自真值表。与非门和或非门被称为万能门，因为仅使用与非门（或仅使用或非门）就可以构建任何电路。
Truth table construction: For a given logic expression (e.g. A AND (NOT B) OR C), list all possible input combinations and evaluate the output. Number of rows = 2ⁿ for n inputs.
真值表构建： 对于给定的逻辑表达式（例如 A AND (NOT B) OR C），列出所有可能的输入组合并计算输出。对于 n 个输入，行数为 2ⁿ。
Logic circuits to expression: Trace a circuit diagram and write the Boolean expression. Conversely, draw a circuit for a given expression.
从逻辑电路到表达式： 追踪电路图并写出布尔表达式；反之，针对给定表达式画出电路。
Boolean simplification: Apply simple Boolean identities (A AND 0 = 0, A OR 1 = 1, A AND NOT A = 0, De Morgan’s laws) to reduce an expression.
布尔化简： 应用简单的布尔恒等式（A·0=0，A+1=1，A·¬A=0，德摩根定律）来化简表达式。
Half and full adders: Half adder: inputs A, B; outputs Sum (A XOR B), Carry (A AND B). Full adder: includes Carry-in. Understanding how they combine to add multi-bit numbers.
半加器与全加器： 半加器：输入 A、B；输出和（A XOR B），进位（A AND B）。全加器：包含进位输入。理解它们如何组合以完成多位数的加法。

9. Databases | 数据库

Databases organise data so that it can be easily accessed, managed and updated. The relational model is the focus, using tables linked by primary and foreign keys. SQL is used to query data. You should be able to design a simple database and write basic queries.

数据库用于组织数据，使其易于访问、管理和更新。重点是关系型模型，使用通过主键和外键关联的表。SQL 用于查询数据。你需要能够设计简单的数据库并编写基本的查询语句。

Flat-file vs relational: Flat-file has a single table, leading to data redundancy and inconsistency. Relational uses multiple linked tables, reducing duplication.
平面文件与关系型： 平面文件只有一个表，会导致数据冗余和不一致。关系型使用多个相互关联的表，减少重复。
Key fields: Primary key (unique identifier for a record, e.g. StudentID), foreign key (a field in one table that links to the primary key of another). Composite and candidate keys may also be mentioned.
键字段： 主键（记录的唯一标识符，如 StudentID），外键（一张表中链接另一张表主键的字段）。可能还会提到复合键和候选键。
Entity-relationship diagrams (simple): Represent tables and their relationships (one-to-one, one-to-many, many-to-many) using simple notation.
实体关系图（简单）： 使用简易符号表示表及其关系（一对一、一对多、多对多）。
SQL queries: SELECT … FROM … WHERE … ORDER BY. Use conditions with AND, OR, LIKE (and wildcards % and _), BETWEEN. Aggregate functions: COUNT, SUM, AVG, MAX, MIN may be used in SELECT.
SQL 查询： SELECT … FROM … WHERE … ORDER BY。使用带有 AND、OR、LIKE（及通配符 % 和 _）、BETWEEN 的条件。聚合函数：COUNT、SUM、AVG、MAX、MIN 可在 SELECT 中使用。
Data types in databases: Integer, decimal, varchar (variable length text), date, boolean. Select appropriate types for given fields.
数据库中的数据类型： 整型、小数、varchar（可变长度文本）、日期、布尔型。为给定字段选择合适的类型。
Data integrity and validation: Presence check, range check, format check, length check. Explain how these prevent erroneous data entry.
数据完整性与验证规则： 存在性检查、范围检查、格式检查、长度检查。解释这些规则如何防止错误的数据输入。

10. Ethical, Legal and Environmental Impacts | 伦理、法律与环境影响

Computing technology has broad societal implications. The WJEC syllabus covers digital rights, legislation, and the environmental footprint of technology. You should be able to discuss these topics with balanced arguments, referring to specific examples.

计算技术具有广泛的社会影响。WJEC 大纲涵盖了数字权利、立法以及技术的环境足迹。你应当能够通过平衡的论点来讨论这些话题，并引用具体实例。

Data protection and GDPR: Principles of data protection – data must be processed lawfully, kept secure, not kept longer than necessary. Individuals have the right to access their data.
数据保护与 GDPR： 数据保护原则——数据必须依法处理、确保安全、保存时间不得超过必需。个人有权访问自己的数据。
Computer Misuse Act: Offences: unauthorised access to computer material, unauthorised access with intent to commit further offences, and unauthorised acts with intent to impair operation (e.g. DoS).
计算机滥用法： 犯罪行为：未经授权访问计算机资料、意图实施进一步犯罪的未经授权访问，以及意图损害计算机运行的未经授权行为（如拒绝服务攻击）。
Copyright and intellectual property: Software piracy, illegal downloads. Creative Commons licences as an alternative to traditional copyright.
版权与知识产权： 软件盗版、非法下载。知识共享许可作为传统版权的一种替代方案。
Digital divide: Unequal access to technology due to economic, geographical or social factors. Discuss how it affects education and job opportunities.
数字鸿沟： 由于经济、地理或社会因素导致的科技访问不均。讨论它如何影响教育和就业机会。
Environmental issues: E-waste (disposal of old devices, toxic materials), energy consumption of data centres, manufacture impact. Solutions: recycling schemes, energy-efficient hardware, ‘green computing’.
环境问题： 电子废弃物（旧设备处置，有毒物质）、数据中心的能源消耗、制造过程的影响。解决方案：回收计划、节能硬件、“绿色计算”。
AI and automation: Potential job displacement, but also creation of new roles. Bias in algorithms and the need for ethical AI design.
人工智能与自动化： 潜在的就业岗位被取代，但同时也会创造新角色。算法偏见以及伦理化 AI 设计的必要性。

11. Exam Technique and Pitfalls | 考试技巧与常见易错点

Even with strong subject knowledge, exam technique can make a big difference. The following tips are drawn from common mistakes seen on WJEC IGCSE Computer Science papers. Practise applying them under timed conditions.

即便拥有扎实的学科知识，考试技巧仍能带来显著不同。以下建议源自 WJEC IGCSE 计算机科学试卷中常出现的错误。在限时条件下练习运用这些技巧。

Command words: ‘State’ – give a brief fact. ‘Describe’ – give details. ‘Explain’ – give reasons (use ‘because’). ‘Compare’ – similarities and differences. ‘Discuss’ – present both sides with a conclusion.
指令词： “State/列出”——给出简要事实。“Describe/描述”——提供细节。“Explain/解释”——给出原因（使用“因为”）。“Compare/比较”——异同点。“Discuss/讨论”——呈现正反两面并得出结论。
Show working: In calculations (file sizes, conversion), always show steps; credit is awarded for method even if the final answer is wrong.
展示过程： 在计算题中（文件大小，进制转换），始终展示步骤；即使最终答案错误，方法正确也可以得分。
Units: Include correct units in your final answer (bits, bytes, KB, seconds, Hz, etc.).
单位： 最终答案要包含正确的单位（bits、bytes、KB、seconds、Hz 等）。
Pseudocode interpretation: When reading an unfamiliar pseudocode algorithm during the exam, make a quick trace table on rough paper to follow the logic.
伪代码解读： 考试中阅读不熟悉的伪代码算法时，在草稿纸上快速画出追踪表以理清逻辑。
Justify choices: When asked to choose a storage device, network topology, or data type, always explain why it fits the scenario, not just the device name.
论证选择： 当要求选择存储设备、网络拓扑或数据类型时，务必解释它为何适合该场景，而不仅仅是给出名称。
Time management: Allocate time based on marks per question; if you get stuck on a 2-mark question, move on and return later. 6-mark questions need more structured, extended writing.
时间管理： 根据每题的分数分配时间；如果在 2 分题上卡住，先往下做，稍后再回来。6 分题需要更有条理的、扩展性的书写。

12. Putting It All Together – A Final Self-Check | 综合自检清单

Use this final checklist to gauge your readiness. Tick each item only if you can confidently explain it or solve a related problem from memory. Focus your last revision sessions on any un-ticked items.

使用这份最终清单来评估你的准备程度。只有当你能够自信地解释某项内容

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Final Revision Checklist for IGCSE WJEC Computer Science | IGCSE WJEC 计算机：期末复习提纲