按建标[2003]206号文的规定，环境保护费的计算公式为环境保护费=( )×环境

用括号中所给词的适当形式填空。

1. She has two hands and two ________ (foot).

2. She has got a ________ (print).

3. He checks the train timetable, but he doesn't buy any ________ (ticket).

4. This is the ________ (one) lesson of the book.

5. Are there any ________ (mouse) in your house?

6. Many ________ (visit) come to Beijing every year.

7. Tony ________ (not visit) his grandparents, but he often sends emails.

8. I don't know how ________ (download) music from the Internet.

9. September is the ________ (nine) month of the year.

10. Do they often use the Internet to send emails and ________ (photo)?

太阳对地球有相当大的万有引力，但它们不会靠在一起，其原因是

A．地球对太阳也有万有引力，这两个力大小相等，方向相反，互相平衡了

B．地球和太阳相距太远了，它们之间的万有引力还不够大

C．其他天体对地球也有万有引力，这些力的合力为零

D．太阳对地球的万有引力充当向心力，不断改变地球的运动方向

集装单元化是物流现代化的标志，其实质就是要形成集装单元化系统。( )

仅有一条眼动脉肌支供应的眼外肌是()

A．上直肌

B．下直肌

C．内直肌

D．外直肌

E．以上均是

电子调速器就是由电子装置及液压伺服机构组合起来的透平控制系统。