题目

When it ______ advertising, consumers need to be educated about techniques used by advertisers.    A. comes up    B. comes about    C. comes out    D. comes to   答案：D  下列物质中属于天然高分子材料的是(　　)A.棉花　    　B.塑料　      　C.尼龙　      　D.羊毛