题干

如图所示的家庭电路中,闭合开关后灯泡不亮。用试电笔检测插座的两孔,发现只有插入右孔时氖管才发光。用试电笔检测A点氖管发光,检测B点氖管不发光。发生这一现象的原因可能是(  )

A:灯泡短路

B:灯丝断了

C:开关接触不良

D:插座短路

上一题 下一题 0.0难度 选择题 更新时间:2018-10-16 02:50:46

答案(点此获取答案解析)

B

同类题5

阅读理解

    Hundreds of years ago, news was carried from place to place by people on foot or by horse. It took days, weeks and sometimes months for people to receive news. Now it is possible to send words and pictures around the world in seconds(秒). Billions of people learn about news stories of their own country and all over the world every day, either by watching TV or reading newspapers. Newspapers have been an important part of everyday life since the 18th century. Many countries have hundreds of different newspapers. How do newspaper editors(编辑) decide which news stories to print (印刷)? Why do they print some stories and not others? What makes a good newspaper story?

    Firstly, it is important to report new stories. TV stations can report news much faster than newspapers. Yet, newspapers give more about the same story. They may also look at the story in another way, or they may print completely (完全地) different stories to those on TV.

    Secondly, a news story has to be interesting and unusual. People don't want to read stories about everyday life As a result, many stories are about some kind of danger and seem to be "bad" news. For example, newspapers never print stories about planes landing safely, instead they print stories about plane accidents.

    Another factor(因素) is also very important in many news stories. Many people are interested in news in foreign countries, but more prefer to read stories about people, places and events (事件) in their own country. So the stories on the front page in Chinese newspapers are usually very different from the ones in British, French and American newspapers.