问题 多选题

原来静止的点电荷在只受电场力作用时(  )

A.一定从场强大的地方向场强小的地方运动

B.一定从电势高的地方向电势低的地方运动

C.一定从电势能大的地方向电势能小的地方运动

D.电场力一定做正功

答案

A、静止开始的电荷会沿着电场力的方向运动,但此方向的场强不一定减小,故A错误;

B、如果是负电荷,运动方向与场强相反,故电势会增大,故B错误;

C、由于电荷只受电场力,从静止开始运动,因此电场力做正功,根据电场力做功量度电势能的变化,所以电势能减小,故C正确.

D、由于电荷只受电场力,从静止开始运动,因此电场力做正功,故D正确;

故选CD.

单项选择题
完形填空

阅读表达(共5小题;每小题3分,满分15分)

阅读下面的短文,根据短文内容回答下列小题。

Cell phones are everywhere-everywhere except Aztec High School.

A new policy put in place at the beginning of the school year by the Aztec School Board forbade cell phones from the school’s campus.

“They are interrupting the educational process,” said Kirk Carpenter, the Aztec High School headmaster. “There is no educational benefit from having them here.”

The new policy started recently afrer long discussions between school and district managers. Aztec school officials said that cell phone use had become a problem during testing sessions.

Carpenter said, “There are also a lot of issues with cell phones. The bottom line(问题的关键) is that they are not in line with what we are trying to do bere, which is providing an education for our students.”

Although the headmaster has heard of no serious objections to the new rule, the complaint he hears most often is parents’ being concerned about contacting students directly in case of an emergency.

“That actually slows down the process,” said Carpenter. “If a parent calls a student’s cell phone, it still needs to go through the office. We can’t just let the student leave school. We don’t know who is on the line. They will still need to call the office to get their children free to leave.”

“If you need to contact a student, you can                      and they will give a message to the student. It still works well,” he added.

Aztec official Linda Paul said, although she never imagined the effect cell phones would have on education, she supports the decision made by the school. Paul added that AHS is not the only campus in the district to have taken such measures.

Cell phone use for teachers, of course, is a different matter. “We hope our teachers know enough not to be on the phone during class, ” Paul said. “I have never seen one of my teachers on the phone during class. ”

小题1:What is the best title for the passage? (no more than 10 words)

                                                                   

小题2:Fill in the blank in the eighth paragraph with proper words or phrase to complete the sentence. (no more than 10 words)

                                                                   

小题3:Which sentence in the passage can be replaced by the following one?

In the campus of AHS, the students’ having cell phones doesn’t do good to education.

                                                                   

小题4:What’s your view about the ban on having cell phones in high school ? Why? ( no more than 30 words)

                                                                   

                                                                   

小题5:Translate the underlined sentence in the sixth paragraph into Chinese.