题干

为了比较甲、乙两种金属的活动性强弱和相对原子质量大小,小科设计了一套实验装置(如右图),他取两种金属(表面积相同)各m克,分别加入足量的稀硫酸(相同质量和质量分数)进行反应,在相同条件下测定不同时间内收集到的气体体积,实验记录如下表:

反应时间(秒)

20

40

60

80

100

120

140

收集到的气体体积(毫升)

甲金属

25

60

95

130

160

170

170

乙金属

30

75

120

150

150

150

150

上一题 下一题 0.0难度 选择题 更新时间:2012-03-10 10:19:07

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同类题2

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Tired of traditional running? Well, maybe it's time to try using your hands instead. That's what Shaun McCarty and other Australians are doing — running on all fours. ____

    McCarthy, who comes from Melbourne, Australia, said he's the one behind the term “crunning.” “It's not crawling, it's not running.” he said. “Crunning is a better workout than running. It puts more of an emphasis(着重)on the body than traditional running does. ____ ”

    McCarthy thinks that he gets much more exhausted after crunning, so he believes it must burn more calories than running.

     ____ Some believe crunning could result in bad shoulder injuries or broken noses.

    But McCarthy is not worried. Many Melbourne residents have been seen running around on all fours. ____ In the Chinese city of Zhengzhou, crawling, a much slower version of crunning, has been a favourite activity for many years. According to some people there, the exercise is believed to date back two thousand years to the Han Dynasty.

     ____ Then McCarthy advises you to buy some good shoes, hand gloves and most important of all, a face mask!

A. Ready to give crunning a try?

B. As it turns out, they are not the only ones.

C. Crunning seems more difficult than traditional running.

D. It really exercises your legs and shoulders at the same time.

E. It's part of the Internet's latest fitness activities: “Crunning.”

F. However, many are not sure if it is the right exercise for humans.

G. He warns, however, that he can't say whether crunning is potentially harmful.