问题 单项选择题

安徽天星野生动物园医院设有一排装动物的笼子,每只笼子只装一只动物。为了避免打搅动物,医院不安排某种捕食者和被捕食者相邻居住。能够接受的动物的物种是O、R、S、T、U。它们之间仅有的捕食关系如下:
(1)O捕食R。
(2)U捕食R。
(3)O捕食S。
(4)S捕食T。

如果医院把5种动物放在5个连续的笼子里,下列哪一项一定正确

A.只O和U可以放在5个笼子的顶端。

B.只有O和R可以和T相邻。

C.S和U不可以被放在两个相邻的笼子里。

D.任何动物都可以放在5个笼子的最中间。

答案

参考答案:D

解析: RSUTQ的排列可以排除A、B和C,正确答案为D。

单项选择题

Congress makes the laws in the United States. It has two pans, which are more or less equal in power. They are known as the House of Representatives and the Senate. The House of Representatives is larger than the Senate whose 100 members (two from each state) serve for six years. The 435 members of the House are elected every two years, and the number from each state is determined by the population of the state. For example, California, which has a large population, has 43 representatives, while the State of Nevada has only one.

The House and Senate are divided into small groups which take care of special matters such as education or foreign affairs. The most important work of Congress is often done in these groups, which are called subcommittees.

According to the Constitution of the United States, a senator must be at least 30 years old and he must have been a citizen of the United States for nine years at the time of his election. To be elected to the House a person must be 25 years old and must have been a United States citizen for seven years. At the present time, members of Congress include businessmen, farmers, teachers, and especially lawyers. In general, senators are better known than representatives because they are fewer in number and serve for a longer time. Many American presidents served in Congress before they became president.

The number of the members in the House from each state ().

A. is fixed, two from each state

B. depends on how many people the state has

C. depends on the size of the state

D. depends on the location of the state

单项选择题