9. Operation rooms should be kept free ______ bacteria of any kind.

A. with　　 　　　　　　 B. for　　 　　　　　　　　　 C. from　 　　　　　　　 D. to

8.--- How did you manage to get such a nice old painting?

　 ---Quite _______.

A. by accidents　　 　 B. by a chance　 　　　 C. by accident　 　　　 D. by incident

7. Most young people don’t want _____ the kind of life that their parents ______.

A. to lead; used to live　 　　　　　　　　　　 B.　 living; used to live　

C. to live; used to living　 　　　　　　　　　　 D. leading;

6. I always look _____ those who never look _____ others, even though they have achieved great achievements.　

A. down on; up to　 　　　　　　　　　　　　　　 B. down upon; up to　

C. forward to; down on　 　　　　　　　　　　 D. up to; down on

5.　 Stop _______me and do what you have been told.

A. to argue with　 　 B. arguing with　 　　　 C. arguing　 　　　　　　　　　 D. to argue

4.　 It is required by the authorities of school that students should be treated ______ by their teachers but how can a teacher respect them when the students show no respect for him?

A. in respect　 　　　　　 B. with respect　 C. for respect　 　　　　　 D. by respect

3.　 Before my father moved off, he told me again and again that I should ______ the rules and regulations of the school.

A. make　　 　　　　 B. watch　　 　　　　 C. remain　　 　　　　　　 D. observe

2.　 Measures have to be taken to teach young people how to ______ themselves both in family and in school. They don’t know the basic manners.

A. do　　　 　　　　　　 B. perform　　 　　　　 C. behave　 　　　　 D. work

从A、B、C和D四个选项中，选出可以填入空白处的最佳选项。

1.______ the traffic jam, he didn’t catch his plane, which was reported to have crashed soon after it took off.

A. Because of　　 　　　 B. On account of　　 C. Due to　　 　　　　　 D. Thanks to

44. 某种自花传粉的豆科植物，同一植株能开很多花，不同品种植株所结种子的子叶有紫色也有白色。现用该豆科植物的甲、乙、丙三个品种的植株进行如下实验。

分析回答：

(1)在该植物种子子叶的紫色和白色这一对相对性状中，显性性状是　　　　　　 。如果用A代表显性基因，a代表隐性基因，则甲植株的基因型为　　　　　　 ，丙植株的基因型为　　　　　　　　　 。

(2)实验三所结的紫色子叶种子中，能稳定遗传的种子占　　　　　　　 。

(3)实验四所结的297粒紫色子叶种子中杂合子的理论值为　　　　　　 粒。