问题 选择题

小明同学为探究X、Y、Z三种金属的活动性顺序,做了以下实验:①把X和Y分别放入稀盐酸中,Y溶解并产生氢气,X不反应.②把X和Y分别放入Z的盐溶液中,在Y的表面有金属Z析出,而X没有变化.根据以上实验事实判断,X、Y、Z三种金属活动性顺序由强到弱排列正确的是(  )

A.X>Y>Z

B.Y>X>Z

C.Z>Y>X

D.Y>Z>X

答案

Y能与酸反应放出氢气而X不能,说明Y的活动强比X强;Y能从Z的盐溶液中置换出Z,说明Y的活动性比Z强,X不能置换盐中的Z,则X的活动性不如Z强;

综上所述,X、Y、Z金属活动性由强到弱的顺序为:Y>Z>X;

故选D

阅读理解

阅读理解。

  NOT all memories are sweet. Some people spend all their lives trying to

forget bad experiences. Violence and traffic accidents can leave people with

terrible physical and emotional scars. Often they relive these experiences in

nightmares.

  Now American researchers think they are close to developing a pill, which

will help people forget bad memories. The pill is designed to be taken

immediately after a frightening experience. They hope it might reduce ,or

possibly erase(抹去),the effect of painful memories.

  In November, experts tested a drug on people in the US and France. The

drug stops the body releasing chemicals that fix memories in the brain. So far the

research has suggested that only the emotional effects of memories may be

reduced, not that the memories are erased.

  The research has caused a great deal of argument. Some think it is a bad

idea, while others support it.

  Supporters say it could lead to pills that prevent or treat soldiers' troubling

memories after war. They say that there are many people who suffer from terrible

memories.

  "Some memories can ruin people's lives. They come back to you when you

don't want to have them in a daydream or nightmare. They usually come with

very painful emotions,” said Roger Pitman, a professor of psychiatry at Harvard

Medical School. “This could relieve a lot of that suffering."

  But those who are against the research say that changing memories is very

dangerous because memories give us our identity (特质). They also help us all

avoid the mistakes of the past.

  "All of us can think of bad events in our lives that were horrible at the time

but make us who we are. I'm not sure we want to wipe those memories out," said

Rebecca Dresser, a medical ethicist.

1. The passage is mainly about _____.  

A. a new medical invention    

B. a new research on the pill

C. a way of erasing painful memories  

D. an argument about the research on the pill

2. The drug tested on people can _____.  

A. cause the brain to fix memories    

B. stop people remembering bad experiences

C. prevent body producing certain chemicals

D. Wipe out the emotional effects of memories

3. We can infer from the passage that _____.

A. people doubt the effects of the pills

B. the pill will stop people's bad experiences

C. taking the pill will do harm to people's health

D. the pill has probably been produced in America

4. Which of the following does Rebecca Dresser agree with?

A. Some memories can ruin people's lives.

B. People want to get rid of bad memories.

C. Experiencing bad events makes us different from others.

D. The pill will reduce people's sufferings from bad memories.  

单项选择题