用适当的介词填空：

1、Macao retuned to our motherland ______ December 20^th, 1999.

2、Is it time ________ breakfast?

3、Hainan Island has a lot of typhoons ________ summer.

4、Tom visits his family ________ Christmas.

5、We go to the Reading Club_________ Monday and Thursday.                   

6、_________the Teachers’ Day, we send cards to our teachers .

7、We have 3 classes_________ the afternoon.

8、We knock__________ people’s doors.
9、He was born __________ 1994.
10、We go to school ___________ the age of 6.