9. Li Rong told me what difficulty she had had ____ English before she came to Canada.

A. learning　 B. learn　 C. learnt　 D. to learn　

8.Charles was alone at home, with______looking after him.

A. someone　 B. anyone　 C. not one　 D. no one

7.--- What were you doing when Lucy ______ in yesterday?

　---- I had just finished my homework and ____ to take a shower.

A. dropping; start　　　　 B. had dropped; started

　C. dropped; have started　 D. dropped;was starting

6. She had just finished her homework_ _____her mother asked her to practice playing the piano yesterday.　

A. when　 B. while　 C. after　 D. since

5. loss　　　　 A. post　　　 B. annoy　　　 C. associate　 D. lemon

第二节 单项选择(共15小题；每小题1分，满分15分)

4. classify　　　 A. quit　　　 B. anxiety　　　 C. survival　 D. appetite

3. react　　　　 A. sacred　　 B. blame　　　 C. criminal　 D. campaign

2. aircraft　　　 A. recently　 B. concentrate　 C. barbecue　 D. concept

第一节 语音知识(共5小题；每小题1分，满分5分)

1.　　 comb　　　 A. abandon　 B. tomb　　　 C. globe　　 D. embassy

41．(12分)酵母菌和大肠杆菌是实验或发酵工程中常用到的微生物，完成下列有关问题：

(1)科学家发现了物质X能延长酵母菌的寿命，这种物质通过一系列反应激活体内一种称为Sir2的酶，这种酶与延长寿命直接相关。

寿命延长的调节方式属于＿＿＿的调节，其特点是快速而精细，如果一变异酵母菌只有在培养基中加入物质C和物质X时才能使寿命延长，则说明该变异酵母菌缺少_____酶。

(2)氨基酸是酵母菌的＿＿＿＿＿级代谢产物。如果要利用酵母菌大量生产氨基酸，则应采用＿＿＿＿＿培养法，使酵母菌处于＿＿＿＿期；如果要利用酵母菌生产单细胞蛋白质，在产品的分离提纯时应采用＿＿＿＿＿和沉淀等方法。