题干

缺锌的人睡觉时常磨牙。这里的"锌"是指(    )

A:元素

B:分子

C:原子

D:离子

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答案(点此获取答案解析)

A

同类题3

阅读下面短文。从短文后各题所给的四个选项A、B、C、D中,选出可以填入空白处的最佳选项。    Once there lived two brothers. The elder was called Simon and the younger Victor. They 1 each other very much, and always took care of one another. Every day they worked from morning 2 night, getting as much grain(谷物) as possible from their fields.
    One late autumn evening, after their work in the 3 was done, Simon said to his wife, "Victor got married last month. He has many bills(账单) to pay. I think I will put a bag of rice in his barn(谷仓). "Oh, that's a good idea," said his wife. "But please don't tell him," said Simon, "If he knows I put the rice there, he will 4 take it."
    So, late that night Simon took a bag of rice to Victor's barn. The next day, while looking at his own barn, he found 5 strange. "I took a bag of rice to Victor's house last night, 6 I still have the same number of bags in my barn. 7 did that happen?"
    Simon decided to take another bag of rice to his brother's barn that night. But the next morning, he found the 8 number of bags in his barn again! "This is very strange," he thought. That night he 9 again. He carried a large bag of rice on his shoulder(肩膀); and walked down the road to his younger brother's house. In the bright moonlight, he could see another 10 coming down the road. He was carrying something on his 11, too. "Younger Brother!" Simon cried, "What are you doing?" "I was 12 you, Older Brother," said Victor, "Your family is 13 than mine. I thought you needed more rice." The two brothers quickly 14 that they had been taking rice to each other. They 15 what had happened. "It is good to have a brother like you," they both said. And they lived happily ever after.

同类题4

阅读下面的文言文,完成小题。

    余阙,字廷心,世家河西武威。少丧父,授徒以养母,与吴澄弟子张恒游,文学日进。元统元年,赐进士及第,授同知泗州事,为政严明,宿吏皆惮之。俄召入,应奉翰林文字。以不阿权贵,弃官归。寻以修辽、金、宋三史召,复入翰林,为修撰。出为湖广行省左右司郎中。会莫徭蛮反,右丞沙班当帅师,坚不往,无敢让之者。阙曰:“右丞当往,受天子命为重臣,不思执弓矢讨贼,乃欲自逸邪!”沙班曰:“郎中语固是,如刍饷不足何?”阙曰:“右丞第往,此不难致也。”阙下令趣之,三日皆集,沙班行。至正十二年,改宣慰司为都元帅府,治淮西,起阙副使、佥都元帅府事,分兵守安庆。于时南北音问隔绝,兵食俱乏,抵官十日而寇至,拒却之。乃集有司与诸将议屯田战守计,环境筑堡寨,选精甲外捍,而耕稼于中。明年,春夏大饥,人相食,乃捐俸为粥以食之,得活者甚众。民失业者数万,咸安集之。升副元帅。十五年夏,大雨,江涨,屯田禾半没,城下水涌,有物吼声如雷,阙祠以少牢,水辄缩。秋稼登,得粮三万斛。俄升都元帅,守安庆。十月,贼薄城下。戊申,贼并军攻东西二门,西门势尤急,阙身当之,徒步提戈为士卒先。士卒号哭止之,挥戈愈力,斩首无算,而阙亦被十余创。日中城陷,城中火起,阙知不可为,引刀自刭,堕清水塘中。阙妻耶卜氏及子德生、女福童皆赴井死。城中民相率登城楼,自捐其梯曰:“宁俱死此,誓不从贼。”焚死者以千计。阙号令严信,与下同甘苦,然稍有违令,即斩以徇。当出战,矢石乱下如雨,士以盾蔽阙,阙却之曰:“汝辈亦有命,何蔽我为!”。稍暇即注《周易》帅诸生谒郡学会讲立军士门外以听使知尊君亲上之义有古良将风烈。卒时年五十六。

(节选自《元史·列传》,有删改)