题干

用铁片与稀硫酸反应制氢气时,下列措施不能使反应速率加快的是   (   )

A:加热

B:不用稀硫酸,改用98%的浓硫酸

C:滴加少量CuSO4溶液

D:不用铁片,改用铁粉

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答案(点此获取答案解析)

B

同类题3

One morning, a blind boy sat on the steps of a building with a hat by his feet .He held a sign which said,“I am blind. Please help me.”
There were only a few coins(硬币) in the hat. A man was walking by. He took out a few coins from his pocket and dropped them into the hat .He then took the sign, turned it around, and wrote some words on it. He put the sign back so that everyone who walked by could see the new words.
Soon the hat began to fill up. A lot more people were giving money to the blind boy. That afternoon the man who had changed the sign came to see how things were. The boy recognized his footsteps and ask,“Are you the one who changed my sign in the morning? What did you write?”
The man said,“I only wrote the truth. I said what you said, but in a different way.”
What he had written was,“Today is a beautiful day, but I can’t see it.”
Do you think the first sign and the second sign were saying the same thing?
Of course both signs told people the boy was blind. But the first sign simply told people to help by putting some money in the hat. The second sign told people that they were able to enjoy the beauty of the day, but the boy could not enjoy it because he was blind.
The first sign simply said the boy was blind, while the second sign told people they were so lucky that they were not blind.
There are at least two lessons we can learn from this simple story.
The first is: Treasure(珍惜)what you have. Someone else has less. Try your best to help those who need your help.
The second is: Be creative. Think differently. There is always a better way.