问题 选择题

下列各组共点力作用在一个物体上,可以使物体保持平衡的是(  )

A.3 N、4 N、10 N

B.2 N、3 N、5 N

C.10 N、10 N、10 N

D.2 N、3 N、4 N

答案

:BCD

三力只要可以构成三角形就可以平衡即:两力之和大于等于第三力,两力之差小于等于第三力,所以BCD对,A错。

阅读理解

Reading Comprehension

  One day a teacher and his student lay down under a big tree near the big grass area. Then the student

suddenly asked the teacher, "Teacher, I wonder how I find my good friend. Can you please help me?"

  Saying nothing for a few seconds, the teacher then answered, "Well, it's a pretty hard and an easy

question."

  "Look that way. There is a lot of grass. Why don't you walk there? Please don't walk backwards,

just walk straight ahead. On your way, try to find a blade (叶片) of beautiful grass and pick it up and then

give it to me, but just one."

  The student said, "Well, OK then…Wait for me…" and walked straight ahead to the grassy field.

  A few minutes later the student came back.

  The teacher asked, "Well, I don't see a beautiful blade of grass in your hand."

  "On my way, I found quite a few beautiful blade of grass, but I thought that I would find a better one,

so I didn't pick it. But I didn't know that I was at the end of the field, and I hadn't picked any because you

told me not to go back, so I didn't go back."

  The teacher said, "That's what will happen in real life. Grass is the people around you, the beautiful

blade of grass is the people that attract you and the grassy field is time. In looking for your soul mate,

please don't always compare and hope that there will be a better one. By doing that, you'll waste your life

time. Please remember 'Time Never Goes Back'."

1. What did the student want to find?

A. A good friend.  

B. Confidence.

C. Skill.

D. Energy.

2. What did the teacher ask him to do?

A. To walk straight ahead.

B. To find more blades of beautiful grass.

C. To find a blade of beautiful grass.

D. To find a beautiful flower.

3. What does the beautiful blade of grass stand for?

A. People.

B. Friendship

C. Time.  

D. Life.

4. What can we learn from the story?

A. We should save our time.

B. We should protect our environment.

C. We can always find many blades of beautiful grass.

D. We shouldn't waste lifetime only in hoping a better thing.

单项选择题