阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出可以填入空白处的最佳选项。

I had a busy weekend last week. On Saturday morning I ___ my mother clean the house. In the afternoon I did my homework and ___ a letter to my pen friend in English. On Sunday I went to the library and ___ two interesting books about animals. In the evening I watched a football match on TV with my father. Although I felt a little ___(4) at night, I was very happy because I had learned a lot. I think it was really a ___ weekend.

【第4空】