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阅读下面的文字,完成各小题。

可燃冰

    可燃冰是由水和天然气在高压、低温情况下形成的类冰状结晶物质,结构上它是甲烷为主的有机分子被包在水分子组成的“笼子”里,由于甲烷是天然气的主要成分,所以其学名是天然气水合物。

    它之所以被称作“可燃冰”,一方面是因为既含水又呈固体,看来像冰,另一方面,甲烷与水分子结合很弱,外界稍加扰动就可以让其分离出来,很容易点燃。

    它燃烧值很高,1立方米的可燃冰分解后可释放出约0.8立方米的水和164立方米的天然气。燃烧产生的能量明显高于煤炭、石油,燃烧污染却又比煤、石油小,更加的清洁环保。

    它储量巨大,广泛分布于全球大洋海底、陆地冻土层和极地之下。有专家估计,其资源量相当于全球已探明传统化石燃料碳总量的两倍。因此,可燃冰是一种有重大战略意义的未来能源,是世界瞩目的战略资源,对我国能源安全及经济发展有着重要意义。

    可燃冰虽然储量大、分布广,但形成年代要比石油、天然气晚得多,覆盖的海底地层普遍是砂质,现有的海底钻井设备开采它就好比在“豆腐上打铁”、用“金刚钻绣花”,稍有不慎就会导致大量砂石涌进管道,造成开采失败。

     2017年5月18日,我国南海神狐海域可燃冰试采实现连续187个小时的稳定产气,首次实现海域可燃冰试采成功。

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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。

    People who are confident really seem to be naturally outstanding and just seem to do everything with more styles than others.____ It is a habit that everyone can develop in life. Try these simple tips to drill and build up your confidence:

1)Admit your shortcomings calmly.

    Do not try to flee from them or cover them. Face them bravely.____ Fight against them every day until the day when you could break away and conquer them.

2)Dress for self-confidence.

    ____ And therefore pay attention to your dress, display your unique physical advantages and exhibit your best image. In addition, on formal occasions such as a business conference or a wedding ceremony, elegant dressing contributes to building your confidence.

3)____

    You should break your routine that deals with the work passively. Concentrate your efforts immediately on overcoming it, because it will make your restless mind at ease and build your self-confidence.

4)Be positive.

    Feel pity neither on yourself nor on others. If you are used to hating and accusing yourself, others would tend to do that and believe it. Instead, you should speak positively about yourself, your progress, and your bright future.____

A. Don't judge a person by appearance.

B. Build your confident vocabulary.

C. Don't put off what you eventually have to do.

D. Actually, true self-confidence is neither born nor acquired overnight.

E. By doing so, you would encourage your growth in a positive direction.

F. Then talk about them to a reliable mate, a friend or a family member.

G. Your appearance could put you into embarrassment or increase your confidence.