问题 选择题

如图为a、b两物体做匀变直线运动的v-t图象,则下列说法中正确的是(  )

A.a、b两物体的运动方向相反

B.t=4s时,a、b两物体速度相同

C.最初4s内,a、b两物体的位移相同

D.a物体的加速度比b物体的加速度大

答案

A、a、b两物体的速度均为正值,物体均沿正方向运动,运动方向相同.故A错误.

    B、由图可知:t=4s时,a、b两物体速度相同.故B正确.

    C、最初4s内,b的图线与坐标横所围“面积”大于a的图线与坐标横所围“面积”,则最初4s内,b的位移大于a的位移.故C错误.

    D、由图b的图线比a的图线陡峭,斜率更大,则b物体的加速度比a物体的加速度大.故D错误.

故选B

问答题 案例分析题
阅读理解

“Old wives’ tales” are beliefs passed from one generation to another. For example, most of us remember our parents’ telling us to eat more of certain foods or not to do certain things. Is there any truth in these teachings? Some of them agree with present medical thinking, but others have not passed the test of time.

Did your mother ever tell you to eat your carrots because they are good for your eyes? Scientists now report that eating carrots can help prevent a serious eye disease called macular degeneration. Eating just one carrot a day can reduce the possibility of getting this disease by 40%. Garlic(蒜) is good for you, too. It can kill the type of virus that causes colds.

Unfortunately, not all of Mom’s advice passed the test of medical studies. For example, generations of children have been told not to go swimming within an hour after eating. But research suggests that there is no danger in doing so. Do sweets cause tooth problems? Well, yes and no. Sticky sweets made with grains tend to cause more problems than sweets made with simple sugars.

Even though science can tell us that some of our traditional beliefs don’t hold water, there is still a lot of truth in the old wives’ tales. After all, much of this knowledge has been accumulated(积累) from thousands of years of experience in family health care. We should respect this body of knowledge even as we search for clear scientific support to prove it true or false.

小题1:The author develops the third paragraph mainly         .

A.by cause and effect

B.by order in space

C.by examples

D.by order in time小题2:Which of the following is TRUE according to the text?

A.Eating garlic is good for our eyes.

B.Carrots prevent people from catching colds.

C.Swimming after a meal is dangerous.

D.Sticky sweets are damaging to our teeth.小题3:What is the author’s attitude toward “old wives’ tales” in the text?

A.Objective.

B.Subjective.

C.Dissatisfied.

D.Curious.小题4:The phrase “hold water” in the last paragraph most probably means “     .”

A.to be valuable

B.to be believable

C.to be admirable

D.to be suitable