[单项选择]Almost overnight, Ames became a hero of environmentalists when his finding led to new and （）bans on certain chemicals.
A. regulations
B. authorities
C. orders
D. suggestions

[单项选择]Ames试验的遗传学终点为
A. DNA完整性改变
B. DNA交换或重排
C. DNA碱基序列改变
D. 染色体完整性改变
E. 染色体分离改变

[单项选择]Ames试验中TA97菌株用于检测
A. 移码突变
B. 碱基置换
C. 非整倍体
D. DNA大段损伤
E. 平衡易位

[不定项选择]Ames实验所用沙门菌的特点（）。
A. 组氨酸基因缺陷
B. 胞壁存在缺陷
C. 化学物质易于透入菌体
D. 修复系统不活化

[单项选择]Ames试验用菌株除了组氨酸突变外，还有一些附加突变，其目的是
A. 增加菌株的抗药性
B. 增加菌株储存过程中的稳定性
C. 提高对致突变物的敏感性
D. 增加细菌的生长速度
E. 抑制细菌的自发回变

[单项选择]Ames试验所应用的体外活化系统 S9混合液中最重要的组分是
A. KCl、MgCl₂
B. 辅酶Ⅱ
C. 葡萄糖-6-磷酸
D. PBS
E. MFO

[单项选择]He became so hungry that he
A. went to sleep
B. ate paper
C. went to the dinner-table
D. kept out of the way

[单项选择]Nancy became a taxi driver because

[单项选择]若该化合物在Ames试验和微核试验中呈阳性结果，则该化合物可能为
A. 遗传毒性致癌物
B. 促癌物
C. 细胞毒物
D. 暂未确定遗传毒性致癌物
E. 免疫抑制剂

[单项选择]Ames试验所用的营养缺陷型菌株在缺乏哪种营养素的培养基上不能正常生长
A. 组氨酸
B. 色氨酸
C. 半胱氨酸
D. 丝氨酸
E. 甘氨酸

[单项选择]Embroidery depicting scenic views became popular in the United States toward the end of the eighteenth century.
A. stating
B. relating
C. portraying
D. celebrating

[单项选择]Photojournalist Margaret Bourke-White became famous for her coverage of significant events during the Second World War.


A. usage
B. camouflage
C. collage
D. reportage

[单项选择]The dinosaurs probably became extinct after a giant asteroid hit the Earth about 65 million years ago. But what ______ if this asteroid ______
A. would have happened; had missed
B. would happen; missed
C. happened; would miss
D. was happening; missed

[单项选择]She had two daughters, became doctors.


A. all the them
B. all of who
C. both of whom
D. all of whom

[单项选择]She finally abandoned her legal career and became a social worker.
A. supposed
B. proposed
C. gave up
D. tired of

[单项选择]He became quite overbearing and domineering once he had become accustomed to the ______ shown to soldiers by the natives. He enjoyed his new sense of power.
A. ability
B. domesticity
C. deference
D. insolence

[单项选择]Undocumented workers became the target of "Operation Safe Travel" because ______.


A. evidence was found that they were potential terrorists
B. most of them worked at airports under threat of terrorist attacks
C. terrorists might take advantage of their illegal status
D. they were reportedly helping hide terrorists around the airport

[单项选择]第一篇 Almost Human Scientists are racing to build the world’s first thinking robot．This is not science fiction：somesay they will have made it by the year 2020 Carol Packer reports Machines that walk，speak and feel are no longer science fiction．Kismet is the name of an android(机器人)which scientists have built at the Massachusetts Institute of Technology(MIT)． Kismet is different from the traditional robot because it Can show human emotions．Its eyes，ears and lips move to show when it feels happy. sad or bored．Kismet is one of the first of a new generation of androids——robots that look like human beings——which Can imitate human feelings．Cog，another android invented by the MIT, imitates the action of a mother．However, scientists admit that So far Cog has the mental ability of a two—year—old． The optimists(乐观主义者)say that by the year 2020 we will have created humanoids(机器人)with brains similar to those of all adult human being．These robots will be designed to look l
A. Critical．
B. Hostile．
C. Objective．
D. Enthusiastic