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问题 单项选择题

下列关于线性表叙述中不正确的是( )。

A．可以有几个节点没有前件

B．只有一个终端节点，无后件

C．除根节点和终端节点外，其他节点都有且只有一个前件，也有且只有一个后件

D．线性表可以没有数据元素

答案

参考答案：A

解析： 线性表要求只有一个根节点，它无前件，所以A是错误的。线性表要求只有一个终端节点，它无后件，B是正确的。线性表要求其他节点都有且只有一个前件，也有且只有一个后件，C是正确的。一个线性表中可以没有数据元素，称为空线性表，D是正确的。

单项选择题

( )领导全国公安机关的督察工作。

A．公安部部长

B．公安部监察委员会

C．公安部党委

D．公安部政治部
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单项选择题

The idea that some groups of people may be more intelligent than others is one of those hypotheses that dare not speak its name. But Gregory Cochran is (1) to say it anyway. He is that (2) bird, a scientist who works independently (3) any institution. He helped popularize the idea that some diseases not (4) thought to have a bacterial cause were actually infections, which aroused much controversy when it was first suggested.

(5) he, however, might tremble at the (6) of what he is about to do. Together with another two scientists, he is publishing a paper which not only (7) that one group of humanity is more intelligent than the others, but explains the process that has brought this about. The group in (8) are a particular people originated from central Europe. The process is natural selection.

This group generally do well in IQ test, (9) 12-15 points above the (10) value of 100, and have contributed (11) to the intellectual and cultural life of the West, as the (12) of their elites, including several world-renowned scientists, (13) . They also suffer more often than most people from a number of nasty genetic diseases, such as breast cancer. These facts, (14) , have previously been thought unrelated. The former has been (15) to social effects, such as a p tradition of (16) education. The latter was seen as a (an) (17) of genetic isolation. Dr. Cochran suggests that the intelligence and diseases are intimately (18) . His argument is that the unusual history of these people has (19) them to unique evolutionary pressures that have resulted in this (20) state of affairs.

3（）

A.of

B.with

C.in

D.against
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