题干

在A+B=C+D反应中,20gA和10gB恰好完全反应,生成5gC.若要生成50克D,至少需要B(  )

A:30克

B:25克

C:20克

D:15克

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答案(点此获取答案解析)

C

同类题2

阅读(甲)(乙)两段文言文,完成小题。

      【甲】林尽水源,便得一山,山有小口,仿佛若有光。便舍船,从口入。初极狭,才通人。复行数十步,豁然开朗。土地平旷,屋舍俨然,有良田美池桑竹之属。阡陌交通,鸡犬相闻。其中往来种作,男女衣着,悉如外人。黄发垂髫,并怡然自乐。

      见渔人,乃大惊,问所从来。具答之。便要还家,设酒杀鸡作食。村中闻有此人,咸来问讯。自云先世避秦时乱,率妻子邑人来此绝境,不复出焉,遂与外人间隔。问今是何世,乃不知有汉,无论魏晋。此人一一为具言所闻,皆叹惋。余人各复延至其家,皆出酒食。停数日,辞去。此中人语云:“不足为外人道也。”

     【乙】仆(1)去月谢病,还觅薜萝(2)。梅溪之西,有石门山者,森壁争霞,孤峰限(3)日,幽岫(xiù)(4)含云,深溪蓄翠。蝉吟鹤唳,水响猿啼,英英相杂,绵绵成韵。既素重(5)幽居,遂葺宇其上。幸富菊花,偏饶竹实,山谷所资,于斯已办(6)。仁智所乐,岂徒语哉!

(                                                                                                                                                                     《与顾章书》)

      【注释】:①【仆】作者谦称。②〔还觅薜萝〕意思是正准备隐居。③(限)遮断。④〔幽岫〕幽深的山穴。⑤〔重〕这里是向往的意思。⑥【办】具备。

同类题3

请阅读下列五个故事简介,将其与上面书橱中陈列的书籍相匹配。其中有一项为多余选项。

⑴Every day the bad Queen asked her mirror: “Mirror, Mirror, on the wall. Who's the most beautiful of us all?” And every day the mirror replies. “You are!”…unitl one day it says, “The Princess!” So the Queen is so angry that she decides to kill the Princess who has skin as while as sonw. She doesn't expect the girl to find not one but seven tiny men.

⑵Finally, the man gets to a lonely island. Luckily, he gets some tools, food and drinks, knives and guns from a broken ship he took. Later, he finds a cave (山洞) to live in. But one day, he finds some large footprints in the sand. Is there anyone else on the land? Who is running towords his cave?

⑶Without parents, the girl is taken to a boarding school. Though she has a hard time there, she gets education and later becomers a teacher. However, she gets so bored with her life that she is thirsty for the outside world. So she sends an ad for a job. Will she get a reply? Will she get everything she fighes for — freedom, fairness and true love?

⑷When the young man meets his long-lost uncle, he finds a magic lamp that changes his life. Inside is a genie (精灵) with the power to make wishes come true. But can even the genie help the young man win the beautiful young girl? And is his long-lost uncle all he seems…?

⑸Here is the boy who is like you in some ways. He thinks school life is boring and looks forword to something exciting. One day, he enters a cave with his friends. They walk deeper and deeper into the cave. Unluckily, their candle is put out and they get lost in the dark. Can they get out of the cave? What other exciting things will they experience?

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