问题
单项选择题
一个非空广义表的表头( )。
A．不可能是子表
B．只能是子表
C．只能是原子
D．可以是子表或原子
答案
参考答案：D
解析：[分析] 一个广义表的元素可以是子表，而子表的元素还可以是子表，形成一个多层次的结构，元素也可以是单个元素。
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一个非空广义表的表头( )。
A．不可能是子表
B．只能是子表
C．只能是原子
D．可以是子表或原子
参考答案：D
解析：[分析] 一个广义表的元素可以是子表，而子表的元素还可以是子表，形成一个多层次的结构，元素也可以是单个元素。
| 完形填空。 | |||
| Mary was ill, so she went to see __1__. "Doctor, I'm not feeling __2__ ," said Mary. "Every time I do my homework, I feel __3__. If I go to school on foot, I have to sit down and __4__ for a few times." The doctor looked over her __5__. At last he said, "__6__ serious(严重的), but I'm afraid you are eating too much." "I don't understand. What do you mean (意思)?" asked Mary. "I mean you eat __7__ food," said the doctor. "Oh! You mean I'm too __8__.That's a problem," said Mary. "What should I do?" "The answer is easy," said the doctor. "If you want to be thinner and healthier, you __9__ eat a lot of food and you should also do much __10__ ." | |||
| ( ) 1. A. her mother ( ) 2. A. terrible ( ) 3. A. hungry ( ) 4. A. stand up ( ) 5. A. carelessly ( ) 6. A. Something ( ) 7. A. too many ( ) 8. A. thin ( ) 9. A. must ( ) 10. A. housework | B. the teacher B. ill B. thirsty B. lie down B. careless B. Anything B. many too B. healthy B. should B. homework | C. the doctor C. good C. tired C. eat food C. carefully C. Everything C. too much C. stressed out C. shouldn't C. shopping | D. her friend D. well D. happy D. have a rest D. careful D. Nothing D. much too D. heavy D. didn't D. exercise |