用所给词的适当形式填空。

1.  December is the __________ (twelve) month of a year.

2.  He takes a shower __________ (one) a week.

3.  Let's __________ (play) games tonight.

4.  The __________ (two)  Sunday in May is Mother's Day.

5. Can you come to the movies with __________ (we)?

用下列哪种水泥配制混凝土时和易性最好（）

A.粉煤灰硅酸盐水泥

B.矿渣硅酸盐水泥

C.普通硅酸盐水泥