【necessary的用法总结大全】在英语学习中，“necessary”是一个非常常见的形容词，表示“必要的、必需的”。它在句子中可以充当表语、定语或宾语补足语。掌握它的正确用法对于提高英语表达能力至关重要。以下是对“necessary”的常见用法进行系统性的总结，帮助大家更全面地理解和运用这个词汇。
一、基本含义
| 词性 | 含义 | 例句 |
| 形容词 | 必要的、必须的 | It is necessary to study hard.（努力学习是必要的。） |
二、常见搭配与用法
1. be necessary (for someone) to do something
表示某人做某事是必要的。
- 例句：It is necessary for students to attend classes regularly.
（学生定期上课是必要的。）
2. it is necessary that...
后面接虚拟语气，表示某种必要性。
- 例句：It is necessary that he leave now.
（他现在必须离开。）
> 注意：在“it is necessary that...”结构中，从句动词要用原形，不加“to”。
3. need + something to be done
表示某事需要被完成。
- 例句：The project needs to be finished by tomorrow.
（这个项目需要在明天之前完成。）
4. have/need to do something
表示必须做某事，常用于口语中。
- 例句：You need to check your email.
（你需要查看你的电子邮件。）
5. the necessary steps
表示必要的步骤。
- 例句：We must take the necessary steps to solve this problem.
（我们必须采取必要的步骤来解决这个问题。）
三、常见错误与注意事项
| 常见错误 | 正确用法 | 解释 |
| It is necessary that he goes now. | It is necessary that he go now. | 在“it is necessary that...”结构中，从句动词要用原形。 |
| He needs to go to hospital. | He needs to go to the hospital. | “hospital”前要加定冠词“the”。 |
| It is necessary for you to learn English. | It is necessary that you learn English. | “that”引导的从句中动词要用原形。 |
四、常见短语与固定表达
| 短语 | 含义 | 例句 |
| a necessary evil | 必要的恶事 | Lying is a necessary evil in some situations. |
| make something necessary | 使某事变得必要 | The new law makes it necessary to register your car. |
五、表格总结
| 用法 | 结构 | 例句 |
| be necessary to do something | It is necessary to do something | It is necessary to finish the report. |
| it is necessary that... | It is necessary that + 动词原形 | It is necessary that we arrive early. |
| need to do something | need to do something | You need to study more. |
| have to do something | have to do something | I have to work late tonight. |
| the necessary steps | the necessary steps | We took the necessary steps. |
| a necessary evil | a necessary evil | War is a necessary evil. |
通过以上内容的总结，我们可以看到，“necessary”虽然简单，但在实际使用中却有多种不同的结构和搭配方式。掌握这些用法不仅能提升语言准确性，还能让表达更加地道自然。建议在日常学习中多加练习，结合例句进行理解和记忆。