1 . I will come around at 10a.m., ________I will be free. (用适当的词填空)

2 . The origin of facial makeup used in Peking Opera can date back to more than 1,400 years ago, ________ leading actors used to wear masks. （用适当的词填空）

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

4 . The National Day falls on October 1st, ______ he was born. （用适当的单词填空）

5 . He will put off the picnic until May 1st, ______ he will be free. （用适当的单词填空）

6 . He will come to see me next July, ________ he won’t be so busy. (用适当的词填空)

7 . I didn't become a serious climber until the fifth grade，________ I went up to rescue a kite that was stuck in the branches of a tree. (适当形式填空)

8 . 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）

9 . We will put off the picnic in the park until next week, ________ the weather may be better.

A．that	B．where
C．which	D．when

10 . I didn't become a serious climber until the fifth grade, _____ I went up to rescue a kite that was stuck in the branches of a tree.

A．when	B．where
C．which	D．why