“as”是英语中常见的介词和从属连词，用法多样。以下是其主要用法总结：
| 用法 | 例句 | 含义 |
| 作为 | She works as a teacher. | 表示身份或职业 |
| 当…时 | As it rained, we stayed home. | 引导时间状语从句 |
| 像…一样 | He runs as fast as a cheetah. | 引导比较状语从句 |
| 由于 | As he was tired, he went to bed. | 引导原因状语从句 |
| 虽然 | As he is young, he knows a lot. | 引导让步状语从句 |
掌握“as”的不同用法有助于提高语言表达的准确性与多样性。
