问题 选择题

某同学从一楼到二楼,第一次是匀速走上去,第二次是匀速跑上去,则下列说法正确的是(  )

A.两次做的功不相同,功率也不相同

B.两次做的功相同,功率也相同

C.两次做的功相同,功率不同,第一次比第二次大

D.两次做的功相同,功率不同,第二次比第一次大

答案

两次从一楼到二楼,克服重力做功相等,根据功率P=

W
t
,时间短的功率大,所以第二次功率大.故D正确,A、B、C错误.

故选D.

填空题
阅读理解

阅读理解

     On Tuesday,,a new study published in the American Heart Association's journal Circulation:Heart

Failure revealed that women who ate five or more dishes of baked fish had a thirty percent lower risk of

heart failure in comparison to women who ate less than one dish a month.

     Researchers examined the diets of 84,493 women,,whose ages ranged from 50 to 79.The women who had eaten lots of baked fish like salmon (鲑鱼),,were more healthy than those who mostly ate tuna (金枪鱼)or white fish.Eating baked fish also appeared to provide a protection against high blood pressure.The

study also found that those women who ate more baked fish were likely to have a lower weight,,exercise more and eat more fruits and vegetables in comparison to those who ate fried fish.

     Researchers noted that past research had discovered the fatty acids (脂肪酸)in fish probably

decreased the risk of high blood pressure by improving blood pressure along with heart and blood

functioning.This study showed the link between eating fish and heart failure risk but it was not designed to

show cause and effect.

     This study also showed that just by eating one dish of fried fish a week led to a 49% greater risk of

heart failure,,and eating fried fish led to lower fiber (纤维)intake and higher calorie (卡路里)intake.

     The American Heart Association suggested eating a minimum of two dishes of fish especailly fatty fish

each week.

1. Compared to the women who ate fried fish those who ate more baked fish could ________.

A. be more relaxed  

B. be more healthy

C. eat more every day  

D. raise blood pressure

2. Which kind of fish is BEST for you according to the author?

A. Baked tuna.  

B. Baked salmon.

C. Boiled salmon.  

D. Fried white fish.

3. According to this passage,,which one is TRUE?

A. The fatty acids in fish can make one's heart bigger.

B. Eating fish probably helps you take in more calories.

C. The fatty acids in fish can improve blood functioning.

D. The fatty acids in fish can raise blood pressure.

4. If a person eats one dish of fried fish a week,,he or she ________.

A. will take in more fatty acids

B. is less likely to get heart failure

C. will like eating more vegetables

D. has a greater risk of heart failure

5. We can infer from this passage that ________.

A. eating 8 dishes of baked fatty fish a month is good for your health

B. eating more fish can make you live longer

C. the reason why eating fish prevents heart failure has been found

D. the association will make a further research on why eating fish lowers the risk of heart failure

6. 用30词左右概括文章大意

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