题干

下列物质属于纯净物的是(   )

A:空气

B:碘酒

C:稀有气体

D:液氮

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答案(点此获取答案解析)

D

同类题1

阅读下面的文言文,完成下列各题。

    太祖母昭宪杜太后,定州安喜人也。父爽,赠太师。母范氏,生五子三女,太后居长。既归于宣祖。治家严毅有礼法。生邕王光济、太祖、太宗、秦王廷美、夔王光赞、燕国陈国二长公主。

    周显德中,太祖为定国军节度使,封南阳郡太夫人。及太祖自陈桥还京师,人走报太后曰:“点检已作天子。”太后曰:“吾儿素有大志,今果然。”太祖即位,尊为皇太后。太祖拜太后于堂上,众皆贺。太后愀然不乐,左右进曰:“臣闻‘母以子贵’,今子为天子,胡为不乐?”太后曰:“吾闻‘为君难’,天子置身兆庶之上,若治得其道,则此位可尊;苟或失驭,求为匹夫不可得,是吾所以忧也。”太祖再拜曰:“谨受教。”

    建隆二年,太后不豫,太祖侍乐饵不离左右。疾亟,召赵普入受遗命。太后因问太祖曰:“汝知所以得天下乎?”太祖呜噎不能对。太后固问之,太祖曰:“臣所以得天下者,皆祖考及太后之积庆也。”太后曰:“不然,正由周世宗使幼儿主天下耳。使周氏有长君天下岂为汝有乎汝百岁后当传位于汝弟四海至广万几至众能立长君社稷之福也太祖顿首泣曰敢不如教太后顾谓赵普曰:“尔同记吾言,不可违也。”命普于榻前为约誓书,普于纸尾书“臣普书”。藏之金匮,命谨密宫人掌之。

    太后于滋德殿,年六十,谥曰明宪。葬安陵,神主祔享太庙。乾德二年,更谥昭宪,合祔安陵。”

《宋史·杜太后传》

同类题5

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    Have you experienced times when you feel like you're under too much pressure? I think most of you will say yes. Actually, many things can strike us beyond our control. With an annoying mix of late trains, missed appointments and work deadlines, many of us are living in a constant state of stress. Experts warn, our modern lifestyles means that stress is almost continuous, and comes without the natural release that either fighting or fleeing might provide.____ Conditions vary from mood swings(情绪波动) to anxiety, irritability, nervousness and tiredness. In extreme cases, it can even cause headaches, muscle cramps, and digestive problems. But there are a number of things we can do to manage the symptoms.

    ____

    Balancing blood sugar is essential in lowering stress. To maintain its level, you can try to have one small meal every two-to-three hours that contains protein, for example, breakfast, lunch and dinner plus a mid-morning and mid-afternoon snack. In this case, your blood sugar will be steady.____

    Laugh as you like.

    ____Many studies show that laughter boosts our energy, decreases stress hormones, improves immunity and lessens pains. Try to find humor in life and engage in activities that make you laugh. Don't feel guilty about doing what you love. It will work its magic in your body.

    Schedule your workout timing.

    It could be the time, rather than the way that determines how effective your workouts would be.____Do energy-forming exercises like running or aerobics in the morning, and milder activities in the evening. Try a walk at the end of the day to calm your mind and stretch your muscles.

A. Eat little and often.

B. So will your mood swings.

C. Laughter is the best medicine.

D. These things are activated by laughing

E. The aim of exercise is to boost your energy.

F. Adapt your exercise routine to the biological clock.

G. Living with it can lead to a whole range of health problems.