根据句意和首字母填入所缺单词。

1. You should write everything you have to do next week on the c__________

2.  This Sunday I will have a p__________ lesson.  I'll learn some new music.

3.  Mary can't go on a trip.  She has to study for a g__________  test.

4.  —Would you like a__________ cup of tea?

    —No, thanks. I'm full.

5.  I'm busy on w__________ , but I'm free on weekends.

面积为S的一切矩形中，其周长最小的矩形的边长是______．