用字母表示：

（1）一项工程，甲队独坐a天完成，乙队独坐b天完成．两队合作，完成的天数．______

（2）a和7所得和的3倍除以5的商．______

（3）n除m的商．______．

连词成句。

1. yours, dictionary, is, the

    __________________________________________?

2. in, water, much, is how, there, jar, the

    ________________________________________?

3. now, me, funny, a , John, question, just, asked

    ____________________________________.

4. Susan, is, tell, me, doing, what, can, you

    _____________________________________?

5. who, the, under, Tom, standing, boy, is, the, tree, is

    ______________________________________