如图，OABC是平行四边形，对角线OB在轴正半轴上，位于第一象限的点A和第二象限的点C分别在双曲线y= $\frac{k_1}{x}$ 和y= $\frac{k_2}{x}$ 的一支上，分别过点A、C作x轴的垂线，垂足分别为M和N，则有以下的结论：

① $\frac{AM}{CN}$ = $\frac{\left|k_1\right|}{\left|k_2\right|}$ ；

②阴影部分面积是 $\frac{1}{2}$ （k₁+k₂）；

③当∠AOC=90°时，|k₁|=|k₂|；

④若OABC是菱形，则两双曲线既关于x轴对称，也关于y轴对称．

其中正确的结论是____（把所有正确的结论的序号都填上）．

选出与你所听内容相符的句子（  ）

    Some people think that as more and more people have televisions in their homes, fewer and fewer people will buy books and newspapers. 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?

    Television has not killed reading, however. Today, newspapers sell in very large numbers. And books of every kind are sold more than ever before. Books are still a cheap way to get information and enjoyment. Although some books with hard covers are expensive, many books are printed today as paperbacks (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.

    Books are a wonderful provider of knowledge and pleasure and some types of books should be in every home. Every home should have a good dictionary. A good encyclopedia, though expensive, is useful, too, because you can find information on any subject. Besides, you can have such books as history books, science textbooks, 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.