题干

关于时刻和时间间隔,下列说法中正确的是(   )

A:在时间轴上,时刻对应的是一条线段

B:新年钟声在零时敲响,这个“零时”指的是时刻

C:某同学放学后在校门口等了一刻钟,公交车才来,这个“一刻钟”指的是时刻

D:杨利伟乘坐的神舟五号经历了21时18分胜利返回地面,这“21时18分”指的是时刻

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答案(点此获取答案解析)

B

同类题1

阅读下列短文,从每题所给的A、B、C、D四个选项中选出最佳选项。

C

    "Tom? Are you in bed yet?" called Mrs. White. There was no answer. Mrs. White put down her book and went to her 14-year-old son's room. Tom was sitting in front of a bright computer screen on which a motorbike was running fast.

    "Oh, Tom. You're still playing on that computer game. You must stop now, because it's half past eleven. If you don't go to bed soon, you'll be very tired tomorrow." Said Mrs. White.

    "But I've nearly won the game." Tom said to Mrs. White. She could see the excitement on his face. She sat beside him.

    "You're always playing on the computer. You spend more time on this machine than on your homework."  

    Today more and more families have computers. Parents hope computers can help their children improve their study at school. But many of their children use computers to play games, listen to songs and watch videos instead of studying. We often see that computer net bars are crowded with people, especially young boys. They spend a lot of money competing with the computerized machines. The more they lose, the more they want to win. The result is that they don't want to work or study.

    In some countries, even scientists hate computers. They say computers cause millions of people to lose their jobs or cause them a lot of trouble. Computer game addiction(瘾) is a serious problem in social life. Something should have to be done to solve the problem.