题干

如图所示,a、b是一点光源S射向凸透镜的两条光线.下列说法正确的是(   )

A:点光源S经凸透镜所成的像一定是实像

B:点光源S经凸透镜所成的像一定是虚像

C:a,b两条光线经过凸透镜后的交点可能在主轴上

D:a,b两条光线经过凸透镜后可能不交于一点

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D

同类题5

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     ____. Why read an article in the newspaper, when the TV news can bring you the information in a few minutes and with pictures? Why read the life story of a famous man, when a short television program can tell you all that you want to know?

    ____. Today, newspapers sell in very large numbers. And books of every kind are sold more than ever before. ____Although some books with hard covers are expensive, many books are printed today as paper books (平装本), which are quite cheap. A paperback collection of short stories, for example, is always cheaper than an evening at the cinema or the theater, and you can keep a book for ever and read it many times. Additionally, ____ No matter when you are on the subway or you are waiting at the airport, a book in hand is always a good choice.

     Books are a wonderful provider of knowledge and pleasure and some types of books should be in every home.____. A good encyclopedia (百科全书), though expensive, is useful, too, because you can find information on any subject. Besides, you can have such books as history books, science textbook, cookbooks, and collections of stories and poems. Then from time to time you can take a book of poems off your shelves and read the thoughts and feelings of your favorite poets.

A. Television has not killed reading, however

B. A printed book is a good time killer

C. Every home should have a good dictionary

D. More and more people spend less time doing sports

E. Choosing a good book is just like choosing a friend

F. Books are still a cheap way to get information and enjoyment

G. With the popularity of televisions, some think fewer people will buy books and newspapers