高中总复习英语从句专题练习Ⅰ.单项填空
1. Helen was much kinder to her youngest son than to the others, _______, of course, made the others envy him.
A. who B. that
C. what D. which
2. There were dirty marks on her trousers _______ she had wiped her hands.
A. where B. which
C. when D. that
3.Small computers need small amount of power, _______ means you use less electricity.
A. what　B. that
C. which D. as