as限定性定语从句

引导状语从句的连词as可以用作关系代词,引导定语从句,因而被称作准关系代词.

1.准关系代词as引导限制定语从句,用于以下3个结构中,as在从句中作主语、宾语或表语：

/ such…as

Such people as were mentioned by him were honest.(as作主语)

I’ve never seen such a clever man as he is.(as作表语)

Last term our maths teacher set so difficult an (= such a difficult) examination problem as none of us worked out.

same…as

Modern statemen are often faced with the same problem as defeated the ancient Romans.(as 作宾语)

I like the same book as you do.(as 作宾语)

…as

As many children as came were given some cakes.(as 作主语)

He is as diligent a man as ever lived.(as 作主语)

　　补充：

…as 与 such…that的区别

such…as 引导定语从句；such…that引导结果状语从句.

They talked in such simple English as children could understand.

他们用孩子们能听懂的`简单的英语交谈.

They talked in such simple English that children could understand it.

他们用十分简单的英语交谈,连孩子们都能听懂.

I will provide you with such things as you may need.

我要供给你一些你可以用得着的东西.

He shut the window with such a force that the glass broke.

他如此用力地关门,结果玻璃碎了.

same…as与the same…that的区别：

the same…as指两物相似,the same..描述的是同一物.

This is the same bag as I lost yesterday.

这个书包和我昨天丢失的（书包）相似.（相似物）

This is the same bag that I lost yesterday.

这正是我昨天丢失的那个书包.（同一物）