题目

下列关于淀粉和纤维素的叙述中，正确的是（ ） A . 它们都是混合物 B . 它们都是天然高分子化合物 C . 它们互为同分异构体 D . 它们水解的最终产物都是葡萄糖 答案：A,B,D6．As we all know clothes are necessary and important for human beings．If someone is asked why he or she wears clothes，the answer will probably be"To keep warm and to cover my body"．These are the basic reasons clothes are worn，but people also want to look attractive and appear successful to others．    If people only wore clothes for warmth and to cover their bodies，most clothing would be simple and cheap．In most Western countries，however，clothing is sometimes very expensive．The main reason for this is not the cost the fabric （布料） or the cost of making the clothes．The clothes are expensive because of fashion （时尚）．Successful businessmen，for example，often wear very expensive suits，shirts and ties．Sometimes they pay thousands of dollars for a suit and hundreds of dollars for a tie．It's still just a suit and tie but they pay these prices because of the famous name of the designer．A suit costing much less would be just as warm and would cover the wearer's body just as well． Fashion is constantly （不断地） changing，which means that people who want to be fashionable have to buy new clothes every few months，even if last month's clothes have only been worn once or twice．Some people have wardrobes （衣柜） full of clothes that have hardly been worn but are no longer in fashion．Being fashionable，therefore，can be a very expensive pastime!46．Why do people wear clothes？DA．Only to cover themselvesB．Just to make themselves attractive．C．Just because of fashionD．For a variety of reasons．47．Successful businessmen buy very expensive suits because ofB．A．the cost of the fabric                         B．the famous name of the designerC．the cost of making them                    D．the good packages （包装） 48．According to the passage，fashionable people have toB．A．wear their clothes only once                   B．buy new clothes regularlyC．wear last month's clothes                     D．buy new clothes once or twice 49．From the last paragraph，we can knowA．A．Being fashionable can be very expensiveB．In most western countries，clothing is sometimes expensiveC．It is too difficult for people to catch up with fashionD．Many people can hardly wear what they have bought 50．What is the passage mainly about？DA．Some clothes are very expensive and some are cheap．B．In many countries，clothes can sometimes be very expensive to buyC．People wear clothes to keep warm and to cover their bodies．D．Many people choose their clothes according to what's in fashion．