网络型摄像机应支持采用标准的（）或MPEG-4视频编码标准。A、ONVIF B、H

函数INT(LEN("123．456"))的结果是【 】。

用括号内所给动词的适当形式填空。

1. Tom and Jim _________ (do) their homework at the moment.

2. Tim usually _________ (get) up at six o'clock.

3. Be quick! Li Lei _________ (wait) for us at the school gate.

4. Han Meimei ________ (like) watching TV. She _________ (watch) TV every evening.

    But now she ________ (not watch) TV. She _________ (get) ready for her final exam.

5. It's six o'clock. My teacher ________ (work) in his office.

硝普钠作用是（）

A.减弱心肌收缩力

B.降低心脏前负荷

C.降低心脏后负荷

D.降低心脏前后负荷

E.降低心脏后负荷及增加心肌刺激

自然垄断

小周、小李、小贺、小齐4人把各自的手机放在一个盒子里(手机款式、外观、材质相同)，然后4人每人从盒子里随便拿出一台，问：谁也没拿到自己手机的拿法有多少种( )

A．7
B．8
C．9
D．10