气质无所谓好坏，性格有优劣之分。

有关细菌遗传的描述，哪项是错误的()

A．细菌染色体为环状螺旋DNA

B．突变是指细菌遗传物质的结构发生突然而不稳定的变化

C．紫外线照射可使细菌的突变率明显增加

D．烷化剂处理可使细菌的突变率明显增加

E．X线照射可使细菌的突变率明显增加

从石灰石、纯碱、小苏打、金刚石、盐酸中选择适当物质填空：

（1）可用作建筑材料的是______；

（2）常用于除铁锈的是______；

（3）镶在玻璃刀头上，用来切割玻璃的是______．

下列有关男女生殖与发育知识的叙述，错误的是[ ]

A．男、女的主要性器官分别是睾丸、卵巢

B．人体受精卵的形成部位与胚胎发育场所分别是输卵管和子宫

C．胎儿与母体进行物质交换的主要结构是胚盘

D．男性的输精管结扎后，仍具有男性第二性征，并能产生精子

On May 29, 1973, Thomas Bradley, a black man, was elected mayor of Los Angeles. Los Angeles is the third largest city in the United States, with a population of three million. About sixteen percent of the city’s population are black.
News of this election appeared on the front pages of newspapers everywhere in the United States. Here is how one major newspaper reported the event.
LOS ANGELES ELECTS BRADLEY MAYOR UNSEATING YORTYBLACK WINS 56% OF VOTES
Bradley called his victory over Yorty "the fulfillment of a dream". During his childhood and youth, people had kept telling him, "You can’t do this, you can’t go there, because you are a Negro. " Nevertheless he had won a decisive victory over a man who had been won 43.7 percent.
Los Angeles voters have had many opportunities to judge. Thomas Bradley had to form an opinion of him. The son of a poor farmer Texas, he joined the Los Angeles police force in 1940. During his twenty-one years on the police force he earned a law degree by attending school at night. He was elected to the city council ten years ago.
At the time of the Los Angeles election, three other American cities already had black mayors, but none of those cities had as large a population as Los Angeles. Besides, the percentage of blacks in those other cities was much larger. Cleveland, Ohio, had thirty-six percent black when Carl Stokes was elected mayor of Cleveland in 1967. In the same year Richard Hatcher was elected mayor of Cary. In Newark, New Jersey, sixty percent of the population were black when Kenneth Gibson was elected in 1970. Thus election of a black mayor in those cities was not very surprising.
In Los Angeles thousands of white citizens voted for Thomas Bradley because they believed he would be a better mayor than the white candidate. Bradley had spent forty-eight of his fifty-five years in Los Angeles. Four years ago Bradley lost mayoral election to Yorty. This time Bradley won.

In the author’s opinion, it was surprising that ______.

A. the whites would vote for a black mayor
B. a black mayor would be elected in such a large city
C. a black from a poor farmer’s family could be elected mayor of Los Angeles
D. there would be so many black mayors

智能化系统集成应实现的基本功能有（）。

A.确认火灾后自动解控各层通道上受出入口控制系统控制的门，便于人员疏散

B.安防报警系统、视频监控系统、出入口控制系统报警后，自动联锁楼宇自控系统打开有关层的灯光，并自动录像

C.通过智能卡一卡通系统，对出入口控制系统、安全防范、汽车库管理、考勤记录、资料借阅、内部消费等进行综合管理

D.楼宇自控、火灾报警、视频监控、安防报警、出入口控制及一卡通、广播系统，以及智能电力监控系统、冷冻机组控制系统、群控电梯的控制系统等各个子系统应能提供开放的协议和接口，以便于通过网络传输，实现较高层次的系统集成