题干

把一定质量的a,b,c,d四种物质放入一密闭容器中,在一定条件下反应一段时间后,测得反应后各物质的质量如下,下列说法中正确的是(   )

物质

a

b

c

d

反应前质量/g

6.4

3.2

4.0

2.6

反应后质量/g

5.2

x

7.2

2.6

A:a和c是反应物

B:d一定是催化剂

C:X=2.0g

D:该反应是化合反应

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答案(点此获取答案解析)

D

同类题1

阅读下列短文,从下面每小题的A、B、C、D四个选项中选出最佳选项。

E

    For a Chinese kid, publishing(出版)a book in English is quite a big challenge. But Yang Nianhui,a 15-year-old student from Beijing,has done so.

    She wrote all English—language fantasy novel,The Vampires of Lorania.Foreign Language Teaching and Research Press has published it.It is their first time to publish a high school student's works independently.

    In Yang's 60,000-word novel,she describes a vampire kingdom called Lorania.A brave girl named Rose and a Chinese boy fight with bad guys to keep Lorania peaceful. It discusses the meaning of heroism from the view of a teenager.It tells readers,"A hero is one who chooses to stay and fight for what is right,even if he is afraid."

    Yang studies at the High School Affiliated with Renmin University of China(人大附中).She has spent over five years working on the book.

    As a big fan of English,Yang enjoys reading original novels and watching TV series in English.She is especially interested in fantasy novels.When she was in Grade 5,she read The Chronicles of Narnia by US author C S Lewis(《纳尼亚传奇》).It encouraged her to write her own novel.

    With little experience,she did run into some problems,like how to design the story.

    "I read many other fantasy novels to learn some things.And I kept changing and improving my draft again and again."she said.

    Yang is happy about publishing her first book."It gives me a chance to express my ideas,"she said.She has already started writing a sequel to her book.