1 . We will put off the picnic in the park until next week, ________ the weather may be better. (用适当的词填空)

3 . The story happened in 1769, ____________ there was a war between the two countries. (用适当的词填空)

4 . 他明天将来这里，那时他有空。（非限制性定语从句）（汉译英）

5 . My connection with pandas goes back to my days on a TV show in the mid-1980s, ________ I was the first Western TV reporter. （用适当的词填空）

6 . Mr.Smith owned this oil painting until the early 1990s, ________ he gave it to his grandson. （用适当的词填空）

7 . I never forget this summer vacation, ___________I spent the happy days with my friends.

8 . But my connection with pandas goes back to my days on a TV show in the mid-1980s, _____ I was the first Western TV reporter permitted to film a special unit caring for pandas rescued from starvation in the wild. （用单词适当形式填空）

9 . Some language experts believe that 10,000 years ago, __________ the world had just five to ten million people, they spoke perhaps 12,000 languages between them. （根据句意填空）

10 . Mr. Smith owned this oil painting until the early 1990 s, ____________he gave it to his grandson.

A．which

B．when

C．where

D．who