埃克森的人格层次论中最下层是（）。A.误差因子 B.特殊反应水平 C.一般因子 D.

下列关于高倍显微镜的使用中，正确的[ ]

A．因为藓类的叶片大，在高倍镜下容易找到，所以可以使用高倍物镜

B．在低倍镜下找到叶片细胞，即可换高倍物镜

C．换高倍物镜后，必须先用粗准焦螺旋调焦，再用细准焦螺旋调到物像清晰

D．为了使高倍物镜下的视野亮一些，可使用最大的光圈或凹面反光镜

如果孕妇需要检测胎盘功能，可以检测尿中的（）

A.雌二醇

B.雌三醇

C.雌酮

D.孕酮

E.睾酮

单句改错 

下列句子中各有一处错误,请指出并改正(每处限改一词).

1. Hundreds of people crowded in the church for the wedding.                         

2. There remain a certain doubt among the people as to the practical value of the project.                      

3. There is a real danger which the US will not keep its position on the world economic stage if

the bad situation continues to go on.                          

4. Rather than to waste his time in chatting or playing games on the Internet, Bob borrowed lots

of books to read in the summer holidays.                         

5. What she won the champion of the Winter Olympic Games made us excited.                           

6. If you want to study the nature of the universe, first of all, you must get hang of the origin of it.               

7. It is required that every salesgirl should treat customers with a warm and friendly

manner.                 

8. The children mustn't be tired----- they just have covered

two miles.                         

9. Tom, you must make an apology to your mother. I won't have you speak to her like

that.                    

10. The children watched amazing as the fireworks set off and formed all kinds of beautiful

designs in the sky.                              

目前国内驱铅治疗的常用解毒剂是（）

A.二巯基丙磺酸钠

B.亚硝酸钠－硫代硫酸钠

C.二巯基丁二酸

D.依地酸二钠钙

E.二巯基丙醇

请简单介绍一下永不停机业务。