[填空题]在y轴上的0≤y≤2一段上，有一根细棒，其上每一点处的线密度等于该点到棒两端的距离平方之积，则其质心

听下面一段对话，回答第14至第17题。
 

听下面一段对话，回答第14至第17题。
M: Hi, mom.
W: There you are. I’m getting worried. It’s so late.
M: Yes. I ran into Linda and we went to a pub. She told me a funny thing.
W: Oh What was that
M: Well, she was driving home after work, and she suddenly saw an old lady on her hands and knees in the middle of the road.
W: Really
M: Yes, Linda was so shocked that she stopped suddenly and the car behind crashed into hers.
W: Was she hurt
M: No.
W: And what was the old lady doing
M: I am just coming to that. So Linda got out of her car and saw the old lady pick up something and walk away.
W: Lucky indeed. Linda didn’t run her over.
M: Then a policeman came. But he didn’t believe what Linda said.
W: Well ...
M: Luckily there was a witness, a man waiting for a bus. He saw it all. Guess what the old lady was doingA. Seeking passers-by’s help.
B. Trying to stand up.
C. Looking for something.
D. Calling the police.