1 . 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）

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

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

4 . 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)

5 . 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

6 . Between the two parts of the concert is an interval, ________ the audience can buy ice­cream.

A．when	B．where
C．that	D．which

7 . The book was written in 1946, ____ the education system has witnessed great changes.

A．when

B．during which

C．since then

D．since when