液压系统中传递力和运动的介质是()A、工作液体 B、电力 C、风能 D、控制原件

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问题:

液压系统中传递力和运动的介质是()

A、工作液体

B、电力

C、风能

D、控制原件

考点:矿井维修钳工矿井维修钳工(中级)矿井维修钳工(中级)题库
题型:单项选择题

Zach Linsky, 11, watches TV for 3 and a half hours a day and plays video games every other day. Zach, a sixth grader in Washington, D. C., is an American. But unlike many kids, he doesn’t have a TV, VCR, or computer in his bedroom. He only has a boom box (手提录音机).

The survey of 3,155 kids, aged 2 to 18, shows that they spend 5 hours and 29 minutes on average(平均的) a day using some types of media outside of school, including 2 hours and 46 minutes watching TV, 21 minutes on the computer, 20 minutes playing video games, and 8 minutes on the Internet. The good news: The total includes 44 minutes spent reading.

The survey also shows that those aged 2 to 7 spend 3 hours and 9 minutes watching TV every day and shows that 32 percent in that age group have TV sets in their rooms. Among those aged 8 to 18, 21 percent have computers in their rooms, 65 percent have TV sets, and 61 percent say their parents don’t stop them from watching TV. Nearly 1 in 4 say they watch more than 5 hours a day.

“Kids are living much more lonely lives than ever before,” says Kay S. Hytnowitz. “They just disappear into their rooms and spend all of their time with these media.”

小题1:At what age do children in America spend about five and a half hours on the media a day?

A.Aged 2 to 7.

B.Aged 2 to 18.

C.Aged 8 to 18.

D.Aged 2 to 11.小题2:How long do kids aged 2 to 18 spend reading?

A.46 minutes.

B.21 minutes.

C.20 minutes.

D.44 minutes.小题3:How many kids aged 2 to 7 have TV sets in their rooms?

A.32%.

B.21%.

C.61%.

D.40%.小题4:Why do the children spend all of their time with these media? Because _______.

A.they have too much free time

B.they feel very lonely

C.they like these media

D.they want to find out something小题5:What’s the problem of the kids in America according to the passage?

A.There are too many media now.

B.Kids spend too much time on the media.

C.Kids are too fat.

D.Kids would rather be with friends than the TV.

题型:单项选择题

下列关于水运特点的叙述,正确的是[ ]

A.运量小、运费低  

B.受自然条件限制  

C.速度快、运量大  

D.投资小、运费高

题型:单项选择题
如图所示,分解一个水平向右的力F,F=6N,已知一个分力F1=4N和另一个分力F2与F的夹角为30°,以下说法正确的是(  )

A.只有唯一解

B.一定有两组解

C.可能有无数解

D.可能有两组解

题型:单项选择题

公司环境目标是指降低能源消耗、污染达标排放、提高固废利用、绿化生产环境。

题型:单项选择题

为了扩大出口,凡出口货物无须经我国商检机构检验即可放行出关。 ( )

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