【托福英语语法指南（mdash及从属连词）】在托福英语考试中，语法部分是考生们必须掌握的重要内容之一。其中，从属连词（subordinating conjunctions）是一个常被忽视但极为关键的语法点。正确使用从属连词不仅能够提升句子的逻辑性，还能让文章更加流畅、自然。
什么是从属连词？
从属连词是用来连接主句和从句的词语。它们不能单独成句，必须依附于主句才能表达完整的意思。常见的从属连词包括：because, although, since, if, when, while, unless, until, as, though, even though 等。
从属连词的作用是引导一个从句，说明主句发生的条件、原因、时间、让步等关系。例如：
- Although it was raining, we went out.
（虽然下雨了，我们还是出去了。）
在这个句子中，“although” 引导了一个让步状语从句，说明尽管有困难，主句的动作仍然发生。
常见的从属连词及其用法
1. Because / Since / As
这三个词都表示“因为”，用于引出原因。它们的区别在于语气和使用场合：
- Because 最常用，强调原因。
- I stayed home because I was tired.
- Since 和 As 更加正式，常用于书面语。
- Since you’re tired, you should rest.
- As it was late, we decided to leave.
2. Although / Though / Even though
表示让步，相当于“尽管”。其中 “even though” 更加强调对比。
- Although it was cold, she wore a skirt.
- Even though he tried hard, he failed the test.
3. If / Unless
表示条件。
- If you study hard, you will pass the test.
- Unless you study, you won’t pass.
4. When / While / As
表示时间。
- When I arrived, the meeting had already started.
- While she was cooking, I cleaned the house.
- As the sun set, the sky turned red.
5. So that / In order that
表示目的。
- He worked hard so that he could afford a car.
- She studied in order that she could get into university.
6. Because of / Due to
表示原因，但通常后面接名词或名词短语。
- Because of the storm, the flight was canceled.
- Due to poor weather, the event was postponed.
从属连词的常见错误
1. 误用连词导致逻辑不清
例如：“I like coffee, but tea is better.” 这个句子没有使用从属连词，显得不够严谨。可以改为：“Although I like coffee, I think tea is better.”
2. 忽略从属连词后应接完整的从句
例如：“Because I was tired, go to bed.” 这个句子不完整，应该改为：“Because I was tired, I went to bed.”
3. 混淆从属连词与并列连词
并列连词（如 and, but, or）用于连接两个独立分句，而从属连词只能引导从句，不能单独使用。
如何在托福写作中有效使用从属连词？
在托福写作中，合理使用从属连词可以让句子结构更复杂、表达更清晰。例如：
- “Although many people believe that technology improves our lives, some argue that it has negative effects.”
- “Because of the high cost of education, many students are forced to take on large amounts of debt.”
这些句子不仅展示了对语法的掌握，也体现了逻辑思维能力。
总结
从属连词是托福英语语法中的重要组成部分。熟练掌握它们不仅能帮助你写出更地道的英文句子，还能在写作和口语中展现出更高的语言水平。通过不断练习和积累，你可以逐步提高对这类连词的运用能力，为托福考试打下坚实的基础。
如果你正在备考托福，建议多阅读英文材料，注意观察从属连词的使用方式，并尝试在自己的写作中模仿和应用。这样，你的英语表达将变得更加准确、自然且富有逻辑性。
