按要求改写下列句子，每空一词。

1. We clean the classroom every day.(用tomorrow代替every day)

    We            the classroom tomorrow.

2. Will your mother come back soon?(作肯定回答)

               ,                      .

3. They'll go shopping with us.(改为否定句)  

    They                      shopping with us.

4. The farmers will work on the hill.(画线部分提问)

                      the farmers           ?

5. The students will go back to school in two days.(对画线部分提问)

       _                       the students           back to school?

6. Tommy has five pens and I have two pens.(改为同义句)

    I have three pens                        Tommy.

天然水的pH值一般为（ ）。

A．7.0

B．6.5~7.0

C．7.2~8.5

D．8.0~9.0

E．5.0~9.0