问题 选择题

设在某均匀介质中(如空气)有一发声体P正在发射某一恒定频率的声波.在离P距离为s的地方有一观察者Q听到P发出的声波音调一定,那么以下说法中正确的是(   )

A.当P不动,Q以一定速度远离P时,Q听到的音调变高

B.当Q不动,P以一定速度远离Q时,Q听到的音调变高

C.当P、Q均以一定速度相互接近时,Q听到的音调变低

D.当P、Q均以一定速度相互远离时,Q听到的音调变低

答案

答案:D

根据多普勒效应,声源跟观察者相互靠近时,音调变高,反之音调变低.   

阅读理解

English is spoken as a first language by most people in the USA, Britain, Australia, New Zealand, Ireland and Canada. However, English is spoken all over the world. It is the main language in over 60 countries, such as India, Singapore and in many of the Caribbean and Pacific islands. In those places English is often a second language.

English is also as an important international language in many other countries, like China and Japan. People in these countries use it for business, and travelers to these countries use English when they get there. Other people may learn English because they enjoy reading books in English, listening to British or American music or watching American films.

English has changed a lot these years and still goes on changing. It is no longer right to talk about British English or American English if the speaker doesn’t come from those countries. People in Japan or Korea, for example, may use the American spelling but may not sound like Americans.

English will be the most widely used language in the world in the 21st century. This language no longer belongs to British, American or Australian speakers. It belongs to anyone who can use this language. After you leave school, you will almost certainly need it.

小题1:In how many countries is English spoken as a first language in the world?

A.Five.

B.Four.

C.Three.

D.Six.小题2:In which other countries is English spoken as a main language?

A.Britain, USA and Australia.

B.India, Singapore and many of Caribbean and Pacific islands.

C.China and Japan.

D.New Zealand, Ireland and Canada.小题3:People from other countries learn English for         .

A.passing exams

B.business and traveling

C.reading English books, enjoying English music or watching films

D.Both B and C小题4:If people in Japan or Korea use the American spelling, they         .

A.will speak the same as Americans

B.may not sound like Americans

C.will speak British English

D.will speak English much better小题5:Which topic is the best for the passage?

A.A first language in the world.

B.A second language in the world.

C.English around the world.

D.A useful language.

单项选择题