问题 选择题

将一磁铁插入闭合线圈,第一次插入所用时间为Δt,第二次插入所用时间为Δt2,且Δt2=2Δt1,则(    )

A.两次产生的感应电动势之比为2∶1

B.两次通过线圈的电荷量之比为2∶1

C.两次线圈中产生的热量之比为2∶1

D.两次线圈中的电功率之比为2∶1

答案

AC

前后两次ΔΦ1=ΔΦ2,产生的感应电动势E=n.故有=2∶1;通过的电荷量q=Δt=,故有q1∶q2=1∶1;线圈中感应电流的功率P=,故有P1∶P2=4∶1;线圈中产生的热量Q=P·Δt,所以=2∶1.

阅读理解

For many people the subject of hiccups (嗝) is a joke, but for Harry Mendes, a fifteen-year-old schoolboy from Birmingham, it was something quite different.

His hiccups began one Sunday lunch time and continued day and night for two weeks. After the first week, Harry’s parents took him to hospital, but it took another week for the doctors to cure his attack.

Harry, who is now back at school, described what happened to him.

“When I began to hiccup, I drank a glass of water but that didn’t do any good. That evening I had hiccups every four seconds. We tried everything to stop them. I held my breath and drank cold drinks. My father even tried to give me a shock but that didn’t work either.”

After a week of sleepless nights, he went to hospital. The doctors took an X-ray of his chest but they couldn’t find anything wrong.

“They gave me some medicine and my hiccups slowed down, but it was another week before the medicine worked completely and my hiccups stopped.”

Harry was very lucky. The world record holder is the American farmer Charles Osborne, who hiccupped for sixty-eight years. He stopped in 1990 at last, but nobody knows why.

小题1:Harry’s hiccups lasted ____.

A.a week

B.fourteen days

C.twenty-eight days

D.one month小题2:His hiccups started after he ____.

A.drank a glass of water

B.went to hospital

C.ate an Indian meal

D.finished his homework小题3:His parents decided to take him to hospital when he ____.

A.hiccupped for four seconds

B.held his breath

C.hiccupped at night

D.couldn’t stop hiccupping小题4:His hiccups completely stopped one week after the doctor ____.

A.gave him some medicine

B.took an X-ray of his chest

C.gave him a shock

D.let him drink cold drinks小题5:What does “shock” in this passage mean?

A.震惊

B.休克

C.喷嚏

D.哈欠

填空题