题干

下列现象中,你认为可称为反射的是(  )

A:人一碰含羞草,其叶片马上卷起

B:摆在窗台上的花草向外生长

C:手偶然碰到火会迅速缩回

D:草履虫对环境中温度的变化表现出趋性

上一题 下一题 0.0难度 选择题 更新时间:2014-07-03 02:52:25

答案(点此获取答案解析)

C

同类题4

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   Monday morning is an important time at our school. All of the students go to the playground.
   We listen to music, and we  1 the national flag(国旗) go up.
   Usually, one student gives a talk on Monday mornings. One Monday last year, a boy gave the talk. He was  2 and excited ! When I saw him, I wanted to have a try, too. Can I really do it?
   Last week, our teacher said our class should give the talk. My teacher 3me, "I know you want to have a try. Next Monday, you can give the talk. Go and write something down. Get ready for it, I'm sure you'll do well." "Thank you ," I answered, It was such a great  4 for me ! When I got home , I was excited. I wrote two pages for the talk. I read them again and again. When I read, I asked my parents  5  . I wanted to make my teacher happy.
   Monday morning came. I began to feel  6 When did I last give a talk to so many people ? Never! This was my first time. Could I really do it?  Maybe I couldn't finish the talk.
   When I got to school, we all went out to playground. I  7  in front of everyone. I opened my mouth, but I couldn't say anything. "Take it easy," I said to 8 . " Don't be nervous. You can do it."
   Just then, I looked down at everyone. I saw about 1,000 eyes. They were all looking at me ! I couldn't even stand up. I looked at their eyes more carefully. Their eyes were saying , "You can do it! Don't be afraid, just talk !" I  9a big breath(呼吸). Then I began to talk. It wasn't hard. It was easy. I don't know  10 I finished my talk. But I did it. I felt so good that day. I showed myself
to everyone what I can do.