[单选题] 作业完毕应关闭( ),再断开( ),清扫作业场地。 (1.0分)
A. 电源、电焊机
B. 电焊机、电源
C. 总电源、分电源
D. 分电源、总电源

Mr. Smith had three brothers. When his mother’s birthday was coming, he and his brothers wanted to send her some gifts. Mr. Smith thought the gifts of his brothers were not good enough. He wanted to buy a better one. He heard about an interesting bird. The bird could talk in twelve languages and sing twenty famous songs. He bought the bird and had it sent to his mother. He bought the bird for＄50,000. The day after his mother’s birthday. He called his mother. "What do you think of the bird " he asked. His mother said, "Delicious (味道鲜美) !"

{{B}}How Geniuses Work{{/B}}
Without a doubt, Einstein was a genius. So was Isaac Newton, who invented Physics. He also played a big role in the development of Calculus (微积分学), which some people have trouble comprehending even after extensive classroom study. Another genius, Wolfgang Amadeus Mozart, started composing music when he was 5 years old. Mozart wrote hundreds of pieces before his death in 1760 at age 35.
{{B}}The understanding of genius{{/B}}
According to conventional wisdom, geniuses are different from everyone else. They can think faster and better than other people. In addition, many people think that all that extra brainpower leads to strange behavior. And although geniuses are fairly easy to spot, defining exactly what makes one person a genius is a little trickier. Figuring out how that person became a genius is harder still.
There are two big things that ma
A. Lower than 90.
B. Between 90 and 110.
C. Between 110 and 140.
D. As much as 140 or more.