1 . He stayed there for quite a long time, during ________ time he learned much spoken English. (用适当的词填空)

2 . It is known to us all that the old scientist, ________ life was hard in the past, still works hard in his eighties. (用适当的词填空)

3 . He gave his daughter some money, ________ which she could buy an English-Chinese dictionary. (用适当的词填空)

4 . This is the small house less than 15 square meters, ________ whose roof lives a large family of three generations. (用适当的词填空)

5 . Could you imagine a future changed by technology ________ which our lessons are taught by robots rather than human teachers? (用适当的词填空)

6 . The book was written in 1946, since ________ education system has witnessed great changes. (用适当的词填空)

7 . It is far better for one to drink milk, ________ which one gets health nutrients, than to drink coffee, which contains no nutrients at all. (用适当的词填空)

8 . He has three sons, ________ whom Li lei is the youngest one. (用适当的词填空)

9 . The dog, _________she used to be afraid, is her favourite animal now. (用适当的词填空)