当先行词前有such,so,as时,关系词应当用as.如：
A wise man seldom talks about such things as he doesn’t understand.
He spoke in such easy English as everybody could understand.
At this time of the day,all buses and trolleys have to carry as many passengers as they can.
It is so easy a book as every schoolboy can read.
Let’s discuss such things as we can talk of freely.
另需注意：
This book is written in such easy English as beginners can understand.（定语从句）
This book is written in such easy English that beginners can understand.（结果状语从句）
