在推荐使用寿命的简单压力容器，（）进行定期检验。A、必须 B、不需要 C、需要

The rockets take astronauts and man-made satellites into space. The satellites are used for communication, weather monitoring and research. But how do satellites stay up without falling down?

There are two opposite forces (力量) acting on the satellite. One of them is the force of gravitation (地心引力), which tries to pull the satellite towards the earth. The other force is created by the rotation (旋转) of the satellite around the earth. This force tries to take the satellite away from the earth. With these two forces, the satellite goes round and round. The gravitational pull of the earth (the force which pulls everything towards the ground) is like a rope which keeps the satellite from flying away.

Everything that goes up has to come down. It is only a matter of time before a satellite comes back to the earth. As time goes by, the satellite loses its speed, which makes the gravitational pull stronger than the force pulling it away. This makes the satellite crash (坠落) down to the earth.

小题1:Which of the following uses of satellites is NOT mentioned?

A．communication

B．monitoring the weather condition

C．doing some research

D．taking pictures小题2:The force that pulls the satellite towards the earth is created by ________.

A．the earth

B．the satellite itself

C．the rotation of the satellite

D．the rope小题3:Why can’t the satellites fly away?

A．Because of the force from the earth.

B．Because the satellite is too big.

C．Because of the force created by the rotation of the satellite around the earth.

D．Because people on earth have made ropes to tie the satellites tightly.小题4:The satellite will finally crashes down to the earth ________.

A．when it flies faster

B．when its speed slows down

C．when people cut the rope

D．when there is no electricity in it小题5:Which of the following is TRUE according to the passage?

A．There are four forces acting on the satellite.

B．The force of gravitation makes the satellite go round and round.

C．As time goes by, the satellite will finally fall down.

D．The satellite will stay in space forever.

透过被照体的X线照射到平板探测器的非晶硒层时，由于非晶硒的导电特性被激发出电子－空穴对，即一对正负电子。该电子－空穴对在外加偏置电压形成的电场作用下被分离并反向运动，负电子跑向偏压的正极，正电子跑向偏压的负极，于是形成电流。电流的大小与入射X线光子的数量成正比，这些电流信号被存储在TFT的极间电容上。每个TFT形成一个采集图像的最小单元，即像素。每个像素区内有一个场效应管，在读出该像素单元电信号时起开关作用。在读出控制信号的控制下，开关导通，把存储于电容内的像素信号逐一按顺序读出、放大，送到A/D转换器，从而将对应的像素电荷转化为数字化图像信号。

关于该平板探测器的叙述错误的是（）

A.属于直接转换

B.属于间接转换

C.成像效果好于IP

D.数据转换不经过可见光

E.需要高压电场

梅奥认为，促成社会解体的科技的进步在______中表现得最明显。

明代蒲州商人范世奎经商西北，“义而资益巨，占良田数百亩”。乾隆时，浑源、榆次二州县富商大贾“且多置买田地”。上述材料表明明清时期（）

A.商人仍遵循“以末起家，以本守之”的传统观念

B.商业资本发展并开开始转化为产业资本

C.晋商精明能干，敢于开拓新的领域

D.官商勾结，搞垄断和特权交易

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