题目

下列有关组成细胞的元素和化合物的叙述，正确的是（ ） A . 寒冬来临，植物细胞中的结合水含量下降 B . C、H、O、N是组成生物体内各种酶所必需的元素 C . 细胞中的微量元素如Fe、Mn、Ca等含量很少，但作用很大 D . 氮是构成脱氧核糖核酸和核糖必不可少的元素 答案：B阅读下面的材料，根据所给的首字母提示，用合适的单词填空。We usually buy things in a shop, a market or a supermarket. Shopping always takes too mucht 【1】 . We have to walk around for a long time to look f 【2】 the things we want. Sometimes we have to c 【3】 many heavy shopping bags. We’re always very tired after s 【4】 . Now it’s different from that in the past(过去). We can do many things at h 【5】 , we don’t need to go to the shop. We can buy many good and c 【6】 things on the Internet(因特网), they look nice but don’t cost much. It seems easy and quick, b 【7】it sometimes brings us some trouble(麻烦). The clothes you buy on the Internet are d 【8】 from what you want, or the size is too s 【9】 or too big. You may see many people wear the same clothes in the street. Do you know why? B 【10】 they all buy clothes on the Internet. How interesting!