As能引導(dǎo)幾種從句：
1. As可以引導(dǎo)定語(yǔ)從句。有時(shí)可譯為“正如”。此時(shí)，常常是as從句在前，主句在后。
例如：As we can see, he is a Chinese.
2. As 還可引導(dǎo)原因狀語(yǔ)從句，“因?yàn)椋捎凇?/p>
例如：As he is so lazy, he never cooks by himself.
3. As還可引導(dǎo)時(shí)間狀語(yǔ)從句，“當(dāng)，隨著”
例如：As the weather is colder and colder, the leaves of the tree is less and less.
4. As還可引導(dǎo)方式狀語(yǔ)從句，“按照”
例如：You must do the work as I have told you.
5. As還可引導(dǎo)讓步狀語(yǔ)從句。“盡管”。但是注意，as引導(dǎo)方式狀語(yǔ)從句時(shí)從句必須倒裝。而且這種倒裝和一般的倒裝不一樣。as從句的倒裝一般是把從句的表語(yǔ)或作狀語(yǔ)的副詞提到as之前，（如果表語(yǔ)是一個(gè)帶有不定冠詞a或an的單數(shù)名詞，倒裝后a或an必須省略)。
例如：Though he is a little boy, he knows a lot.如果變成由AS引導(dǎo)，就必須變成：
Little boy as he is, he knows a lot.
Though he works hard, he never succeed.
可變?yōu)?Hard as he works, he never succeed.