<s>Human: 给出一道初中英语语法练习题，要求学生填写适当的代词。
</s><s>Assistant: 好的，请看以下的练习题：

____ are my friends Jack and Jill. ____ are twins.
____ are very good students. ____ always do ____ homework.
Yesterday, I saw ____ in the park. ____ were having a picnic.
I asked ____ if ____ wanted to play soccer. ____ said that ____ were too tired.

请使用适当的代词填空。
</s>