在载玻片的左右两侧各滴一滴草履虫培养液，用解剖针把两滴培养液_爱下问搜题

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问题选择题

在载玻片的左右两侧各滴一滴草履虫培养液，用解剖针把两滴培养液连通起来．当在左侧培养液中放少许食盐时，用放大镜观察到的现象是（　　）

A．大多数草履虫停止运动

B．大多数草履虫向左侧运动

C．大多数草履虫向右侧运动

D．大多数草履虫原地快速运动

答案

实验中在载玻片左侧培养液的边缘放一些食盐，食盐对于草履虫来说是不利的刺激，所以在有盐的一侧的草履虫要逃离，游到右侧没有盐的培养液滴中，可以得出的结论是草履虫具有应激性，能够对外界不同的刺激作出不同的反应．

故选：C

完形填空

We often talk about ourselves as if we have permanent genetic defects （缺陷） that can never be changed. “I’m impatient.” “I’m always behind.” “I always put things 36 !” You’ve surely heard them. Maybe you’ve used them to describe 37 .
These comments may come from stories about us that have been 38 for years—often from 39 childhood. These stories may have no 40 in fact. But they can set low expectations for us. As a child, my mother said to me, “Marshall, you have no mechanical （操作机械的） skills, and you will never have any mechanical ski

lls for the rest of your life.” How did these expectations 41 my development? I was never 42 to work on cars or be around 43 . When I was 18, I took the US Army’s Mechanical Aptitude Test. My scores were in the bottom for the entire nation!
Six years later,   44 , I was at California University, working on my doctor’s degree. One of my professors, Dr. Bob Tannbaum, asked me to write down things I did well and things I couldn’t do. On the positive side, I 45 down, “research, writing, analysis, and speaking.” On the 46 side, I wrote, “I have no mechanical skills.”
Bob asked me how I knew I had no mechanical skills. I explained my life 47  and told him about my 48 performance on the Army test. Bob then asked, “ 49 is it that you can solve 50 mathematical problems, but you can’t solve simple mechanical problems?”
Suddenly I realized that I didn’t   51 from some sort of genetic defect. I was just living out expectations that I had chosen to 52 . At that point, it wasn’t just my family and friends who had been   53  my belief that I was mechanically hopeless. And it wasn’t just the Army test, either. I was the one who kept telling myself, “You can’t do this!” I realized that as long as I kept saying that, it was going to remain true. 54 , if we don’t treat ourselves as if we have incurable genetic defects, we can do well in almost 55 we choose.

D．as far back as

小题7:A hoped B. demanded C. encouraged D. agreed

C．experiences

D．strengthening

A．As a result

B．On the contrary

C．In addition

D．At the same time

单项选择题

目前公众个人全身受照射的年剂量应低于（）.

A.0.5mSv

B.1mSv

C.2mSv

D.5mSv

E.10mSv