平面平行力系处于平衡时，应有独立的平衡方程个数为（）。 A.1 B.2 C.3 D.

Nick is a 14-year-old school boy. His life is full of exams and studies on weekdays. He has little free time. He thinks playing computer games is the best way to make him relax. When he has free time, he sits in front of the computer. Just like that way, he neither eats nor drinks for several hours.

Last weekend, he played games on the computer again. He was too excited and didn't want to move. He didn't have anything for six hours. When he had to go to the bathroom, he found he could not move. He was taken to the hospital. The doctor told him he should do some more different kinds of activities. In other words, he needs more exercise and outdoor activities to make him have a healthy body.

After coming back from the hospital, Nick follows the doctor's advice. He often plays soccer with his friends. Sometimes he still plays computer games on weekends, but he never does it for long. Now, he lives a happy and healthy life.

小题1:How old is Nick?

A．13.

B．14.

C．15.

D．16.小题2:Nick likes       in his free time.

A．riding a bike

B．playing the guitar

C．playing computer games

D．having a school trip小题3:Why was Nick taken to the hospital?

A．Because he was too excited.

B．Because he had a cold in the morning.

C．Because he was too nervous of his studies.

D．Because he couldn’t move after playing computer games so long.小题4:Nick should       to follow the doctor’s advice.

A．go to a movie

B．listen to music

C．take more exercise

D．play computer games小题5:Which of the following is True?

A．Nick is very busy with exams and studies on weekdays.

B．Nick will never play computer games.

C．Nick likes eating and drinking when he plays computer games.

D．Nick has an unhappy and unhealthy life now.

如图所示，若运行方向是从左至右，试说明5-7DG正常解锁应具备的三点检查条件是什么？

经过数字化处理之后的数字波形声音，其主要参数有：取样频率、______ 、声道数目、码率，以及采用的压缩编码方法等。

我国最早的坎儿井是西汉时关中平原的（）。

A.灵渠

B.龙首渠

C.郑国渠

D.红旗渠

（）是炉膛底部的砌砖部分。

A、炉底

B、炉底

C、炉墙