罗次风机在正常情况下，压力改变时，风量变化很小，所以噪音低。（）

下列不是多动综合征的临床表现的是（）

A.别人讲话时常常显得没在听

B.常无法遵守指令，无法完成功课或其他活动中的义务

C.言语发育落后，与人交往困难

D.对来自各方面刺激几乎都有反应

E.对一些不愉快的刺激做出过分反应

电视的图像信号和声音信号是通过________传递的，画面的色彩由红、________、蓝三种色光混合而成。

重W的物体自由放在倾角为α的斜面上，如图4-1-32所示。物体与斜面间的摩擦角为φ_M＜α，则物体（）。

A．静止

B．滑动

C．当W很小时能静止

D．处于临界状态

在柱子吊装中，旋转法的要点是保持柱脚位置不动，并使柱的( )共圆。

A．吊点和杯口中心

B．吊点和柱脚中心

C．柱脚中心和杯口中心

D．吊点、柱脚中心和杯口中心

E

It was December 25. Marie, a 13-year-old Australian girl, was happy. It was Christmas and Marie’s mother was making a very special cake. She put four small coins into the cake and then baked it. The four coins were for good luck. After dinner, Marie and her family ate the cake. They found three coins in the cake and put them on the table. Where was the fourth one It was missing(找不到的), but Marie’s mother didn’t notice.
After Christmas, Marie got sick. She coughed and couldn’t speak. Marie’s parents took her to hospital. Doctors at the hospital looked her over and then said," We are sorry, but we can’t help her. "For 12 years, Marie didn’t speak. But like other common people, she grew up, she got a job, she got married. One day, when Marie was 25 years old, she got a sore throat. She began to cough. She coughed up something small and black. What was it Marie didn’t know. She took it to a hospital. A doctor at the hospital said," This is a coin!" The doctor told Marie," I think you can speak again. \

When did the story begin ( )

A．During Christmas.

B．On Marie’s birthday.

C．Before Christmas.

D．After Christmas.