问题 选择题

以下说法正确的是(  )

A.声音的响度和音色在传播过程中是不发生改变的

B.振动快的物体能够发声,振动慢的物体不能发声

C.发声体的振动停止后,还会发出很弱很弱的声音

D.利用声音的反射可以使声音的响度增大

答案

A、声音的音色在传播过程中是不发生改变的,而声音的响度却在传播过程中是发生改变的,不符合题意;

B、只要是振动的物体就能够发出声音,选项说法不符合题意;

C、当发声体的振动停止后,就不会发出声音,不符合题意;

D、反射回的声波频率相同,会产生共振,所以比没有遮挡物时候要大一些,因此利用声音的反射可以使声音的响度增大,符合题意;

故选D.

多项选择题
阅读理解

Last week, 169 junior 1 students at No. 35 Middle School of Shenyang took their first no- teacher exam. after the teacher handed out the exam paper, he left the room and never came back. A student collected in the papers when the exam ended.

“that test was not only a test of knowledge, but also a test of moral (道德). We wanted to show students how important honesty (诚实) is, “said Cai Wenguo, the school’s headmaster. The school says no cheating(作弊) happened in the test. Next year, it wants 80% of its exams to be without teachers. But students have different ideas.

“I was happy and excited during the exam because my teachers trusted (信任) me. ”said Lang Yudan, a 13-year-old girl in Class 11.

“Schools must trust students a lot not to use invigilators (监考人). But I think it is too early. Some students will cheat if there are no invigilators. And the students will not be able to ask for help when needed.” said Hua Sha.

“I don’t like having invigilators in exams . When they walk around the classroom, they make me nervous. I would get higher marks without them in the room because I would feel more relaxed.” Liu Qingxi said.

“I think it’s very important to have invigilators in exams. Many students want to check their answers with each other after they have finished papers. And they can also keep the classroom in order when something unusual happens. They may make me nervous, but I still think we need them. ” Shangguan Yuan said.

Not using invigilators may be a good idea. But before using it, schools must tell students the importance of honesty and try to find ways to solve something unusual in exams.

1. The passage mainly (主要地) talks about          .

A. how to pass an exam

B. how to make students honest

C. whether there is cheating in exams

D. whether invigilators are needed in exams

2. No. 35 Middle School of Shenyang held a no- teacher exam to         .

A. let the students have a good rest

B. teach the students in a better way

C. help all the students pass the exam.

D. find whether the students were honest

3. From what the students have said , we know          .

A. invigilators really help them a lot

B. all of them think it is a good idea

C. something unusual never happens in exams

D. not all of them agree with the head

4. What does Hua Sha think about no- teacher exams?

A. It’s a good idea to have no- teacher exams but something must be done first.

B. If there are no invigilators, the students will certainly get lower marks.

C. Exams without invigilators will never be held since students are not honest.

D. She thinks it’s the best way to show that schools trust their students a lot.

5. In the sentence “And they can also keep the classroom in order when something unusual happens ” “they” refers to (指)          .

A. students     B. headmasters     C. invigilators     D. schools