问题 选择题
一单匝闭合线框在匀强磁场中绕垂直于磁场方向的转轴匀速转动的过程中,最大磁通量为Φm,最大感应电动势为Em,下列说法正确的是(  )

A.当磁通量为零时,感应电动势也为零

B.当磁通量减小时,感应电动势也在减小

C.当磁通量等于0.5Φm时,感应电动势等于0.5Em

D.角速度等于Emm

答案

答案:D

阅读理解

阅读理解。

     Jason Crole studies in an American high school. As a native of London, the 16-year-old didn't know much

about America's colonial (殖民地的) past before this summer.

     But now Crole can talk a lot about the settlers (移民者), slavery (奴隶制) and the events that led up to the

American Revolution (美国独立战争). He learned about these subjects at a summer program at the College of

William and Mary, Virginia.

     It is a 70-year-old program that gathers high school students from across the US to study early American

history.

     "It's been great and a lot of hard work," said Crole. "This is not a subject really  taught in England, so I'm

learning a lot of new things."

     The program meet from 8 am to 3 pm five days a week. It goes for three weeks. Students go to lectures

and read essays about the time period they are studying. They study history from the founding of Jamestown

through the American Revolution and the Civil War (美国内战).

     As well as leaming about history in the classroom, students also take field trips to historical sites. They visit

Colonial Williamsburg, Jamestown and other sites around Virginia. They learn what life was like during that

time.

     "We hope the students can really leam something about our early history," said Carolyn Sparks Whittenburg,

director of the program. " We offer the program to kids who love history. A total of 111 students were in the

program this summer, but we hope for more next year."

1. The summer program helps high school students to study _______.

A. the settlers

B. the Civil War

C. the American Revolution

D. American history

2. The summer program lasts for _______.

A. seven hours

B. five days

C. three weeks

D. one month

3. Which of the following is true according to the passage?

A. There were hundreds of students in the program this summer.

B. Some students are not quite clear about America's colonial past.

C. Students can take part in the summer program in their high schools.

D. The subject is taught outside the classroom rather than inside.

选择题