题干

金属钒被誉为“合金的维生素”。五氧化二钒(V2O5)中钒元素的化合价为(   )

A:+5

B:+3

C:+2

D:—3

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答案(点此获取答案解析)

A

同类题3

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    崔郾,字广略,姿仪伟秀,人望而慕之,然不可狎也。中进士第,补集贤校书郎,累迁吏部员外郎,下不敢欺。每拟吏,亲挟格,褒黜必当,寒远无留才。三迁谏议大夫。穆宗立,荒于游畋,内酣荡,昕曙不能朝。郾进曰:“十一圣①之功德,四海之大,万国之众,其治其乱,系于陛下。自山以东百城,地千里,昨日得之,今日失之。西望戎垒,距宗庙十舍,百姓憔悴,畜积无有。愿陛下亲政事以幸天下。”帝动容慰谢,迁给事中。敬宗嗣位,拜翰林侍讲学士,旋进中书舍人,谢曰:“陛下使臣侍讲,历半岁,不一问经义。臣无功,不足副厚恩。”帝惭曰:“朕少间当请益。”高釴适在旁,因言:“陛下乐善而无所咨询,天下之人不知有向儒意。”帝重咎谢,咸赐锦、币。郾与高重类《六经》要言为十篇,上之,以便观省。迁礼部侍郎,出为虢州观察使。先是,上供财乏,则夺吏奉助输,岁率八十万。郾曰:“吏不能赡私,安暇恤民?”即以府常费代之。又诏赋粟输太仓者,岁数万石,民困于输,则又辇而致之河。郾乃旁流为大敖②受粟,窦而注诸艚。民悦,忘输之劳。改鄂、岳等州观察使。自蔡人叛,鄂、岳常苦兵,江湖盗贼显行。郾修治铠仗,造蒙冲,驶追穷蹑,上下千里,岁中悉捕平。又观察浙西,迁检校礼部尚书,卒于官。赠吏部尚书,谥曰德。郾不藏赀,有辄周给亲旧,为治其昏丧。居家怡然,不训子弟,子弟自化。室处庳漏,无步庑,至霖淖,则客盖而屐以就外位。治虢以宽,经月不笞一人。及莅鄂,则严法峻诛,一不贷。或问其故曰陕土瘠而民劳吾抚之不暇犹恐其扰鄂土沃民剽杂以夷俗非用威莫能治政所以贵知变者也闻者服焉。

(节选自《新唐书•崔邠传》)

【注】①十一圣:穆宗之前的十一个皇帝。②敖:通“廒”,储存粮食的仓库。

同类题5

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    Will you put others' needs before your own? What 1 will you get if you do? Here is an experience of mine.

    It was a wet day and I had a 2time. I was busy and everyone I talked to was in a bad mood(心情). What's more, I went out without breakfast and I left my 3at home. So I couldn't get lunch and was terribly hungry.

    When I finished my work, I 4to ask my wife to meet me at the door with some money so that I could quickly go to buy 5. Then I quickly made my way home in hope of eating my 6meal of the day at 5:00 p.m.

    As I was halfway home, my wife told me by phone that a friend of ours was in 7and needed a lift(搭便车)home. My mind said, “I will get him 8I get the meal.” But my mouth said, “All right, I'll give him a 9”

    He jumped in the car with a smile on his face and repeated how 10he was that I would drive him home. He told me he usually walked home from his company but that day the 11stopped him from making that journey.

    Traffic was 12. A drive to his home normally took 10 minutes, but that day it took 30 minutes.

    Now you would guess the person that I was helping is a 13friend of mine. But, in fact, he is a friend of a friend's.

    I wonder if I will ever see this person again, but I feel glad I was there when he 14me.

    So you will feel yourself helpful and useful when you 15more about others.