题目

下列物质能被胰蛋白酶分解的是                                        （    ） ①干扰素 ②白细胞介素 ③抗毒素   ④凝集素 A．①②③④    B．①②    C．①③④     D．③④ 答案：A  解析: 外毒素、凝集素、抗毒素化学本质都是球蛋白，干扰素白细胞介素化学本质是糖蛋白。 完形填空。     In many countries old age is a happy time, but in the United States it is quite    1    for old people. Most old people do not live with their children or relative. If they    2    enough money, they buy house or apartments in places where     3    old people live. If they    4    healthy and strong enough to live alone, they live in special homes for old people. There,    5    take care of them. For many North Americans, old age is not a     6    time, Most of them want to    7    young. They try to keep thin and they act (行为) like young people as    8    as possible. They even try to speak the language of     9   . They do not like to grow old because they will not get honor or respect or attention(荣誉,尊敬,注意).Also businesses do not want old people to work for them. So old people usually live alone and they do not have many things to do. Old age   10   be a sad and lonely time for them. (     )1. A. easy         (     )2. A. find         (     )3. A. other        (     )4. A. are          (     )5. A. strangers    (     )6. A. serious      (     )7. A. look         (     )8. A. soon  .      (     )9. A. the children (     )10. A. can         B. the same   B. have       B. the other  B. aren't     B. none       B. wonderful  B. be         B. easily     B. the young  B. must       C. different       C. borrow          C. others          C. become          C. friends         C. happy           C. stay            C. long            C. the old people  C. has to