验证大气压存在的著名实验是______；精确地测出大气压值的实验是______实

下列关于C₆₀的说话不正确的是[ ]

A．C₆₀及金刚石、石墨都是碳的单质  

B．该物质的相对分子质量为720  

C．该物质中碳元素的化合价为+4价  

D．保持该物质化学性质的最小粒子是C₆₀分子

用括号内所给词的适当形式填空。

1. _______ (not believe) him. He tells a lie.

2. Lillian _______ (not have) the green dress

    and she _______ (not do) housework.

3. He even wants _______ (be) a Beijing Opera artist.

4. I like _______ (comedy). ________ (it) are very interesting.

5. His friend's birthday is December ________ (twelve). Mine is April ________ (four).

    I will spend my ________ (nine) birthday this year.

在转动机器附近工作，佩戴下列哪一种物品是最容易引致意外发生?

A.戒指 

B.领带 

C.手表

中国人民解放军政治工作的内涵？