如图所示是某一质点做简谐运动的振动图象，下列说法正确的是 [_爱下问搜题

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问题选择题

如图所示是某一质点做简谐运动的振动图象，下列说法正确的是

[ ]

A．质点振动的周期为7s

B．在第1s末，质点受到的回复力改变方向

C．0时刻与第4s末，质点速度的大小和方向均相同

D．在第5s内，质点的动能转化为势能

答案

答案：D

选择题

根据图片，选择正确的句子。

( ) 1.	A. Don't touch. B. Don't walk on the grass.
( ) 2.	A. What's the weather like today? It's windy. B. What's the weather like today? It's hot.
( ) 3.	A. How does Jack feel? He feels happy. B. How does Jack feel? He feels sad.
( ) 4.	A. What are they going to do next week? They are going to plant trees. B. What are they going to do next week? They are going to pick up trash.
( ) 5.	A. They will watch TV at home tomorrow, won't they? No, they won't. B. They will watch TV at home tomorrow, won't they? Yes, they will.
( ) 6.	A. Can Peter play basketball very well? No, he can't. B. Can Peter play football very well? Yes, he can.
( ) 7.	A. I think computers will replace teachers in the future. So do I. B. I think robots will replace teachers in the future. Neither do I.
( ) 8.	A. What's the matter with Lily? She hurts her ankle. B. What's the matter with Lily? She hurts her knee.
( ) 9.	A. She often washes the clothes at home on Sunday. B. She often sweeps the floor at home on Sunday.
( ) 10.	A. Lily is writing a letter. B. Lily is looking out of the window.

单项选择题

下面对感性认识和理性认识的相互依赖说法不正确的一项是（）。

A.人的感性中渗透着理性的认识

B.理性认识以感性认识为基础

C.感性认识具有局限性，需要发展到理性认识

D.没有感性认识，理性认识就是无源之水