问题 选择题
某质点做简谐运动,其位移随时间变化的关系式为x=5sin(cm),则下列关于质点运动的说法中正确的是(   )
A.质点做简谐运动的振幅为10cm

B.质点做简谐运动的周期为4s

C.在t=4 s时质点的加速度最大

D.在t=4 s时质点的速度最大

答案

答案:D

阅读理解

阅读下文并回答问题。

Colorful fruit and vegetables are good for our health.Their natural colors help protect our bodies from disease.Think about the colors of fruit and vegetables:the red of tomatoes,the orange of carrots,the green of kiwi fruit and the purple of grapes.

You can enjoy eating fruit and vegetables of all colors:green,yellow,orange,blue,purple and white.Each color is unique(独一无二的) and important to our health.These colors work together to protect our bodies.Scientists have studied them and discovered the good of colorful fruit and vegetables.The list below shows the good of some colors in fruit and vegetables:

*Red gives us a healthy heart.It can reduce the risk of heart disease.Red helps prevent cancer and improve our memory.

*Yellow gives us a healthy immune system(免疫系统).It is also good for our eyes.

*White can keep cholesterol(胆固醇)at a low level.

*Green helps prevent cancer.It is good for our eyes,too.It also gives strong bones and teeth.

*Blue helps us keep a good memory as we grow old.It also helps fight cancer and heart disease.

So when you are buying or eating fruit and vegetables,remember: try different colors of fruit and vegetables.

小题1:How many kinds of fruit and vegetables are mentioned in this passage?

___________________________________________________________

小题2:How do the colors of fruit and vegetables protect our bodies according to the passage?

___________________________________________________________

小题3:Does blue help us keep a good memory as we grow old?

___________________________________________________________

多项选择题