题干

纯碱和小苏打都是白色晶体,在日常生活中都可以找到。若要在家中将它们区分开来,下面的方法中可行的是(  )

A:分别放在炒锅中加热,观察是否有残留物

B:分别用干净铁丝蘸取样品在煤气炉的火焰上灼烧,观察火焰颜色

C:将样品溶解,分别加入澄清石灰水,观察是否有白色沉淀

D:在水杯中各盛相同质量的样品,分别加入等体积的白醋,观察反应的剧烈程度

上一题 下一题 0.0难度 选择题 更新时间:2018-12-02 05:37:04

答案(点此获取答案解析)

D

同类题4

阅读理解

    I was always blamed for watching too much cartoons. As I have said goodbye to my teenage, I shift to watching more movies to prove that I was a grown-up. Surprisingly, I found that movies have something in common with cartoons. They are unrealistic.

    Sometimes movies give people hope, including the hope of justice, the hope of tomorrow and almost everything else. A great number of people were once touched by certain movies. From time to time, movies try to deliver some decisive ideas to the audience. In this way, movies do cheer up many people to go on with their lives.

    It seems that there is a set formula in movies. We usually see the hero or heroine in the movies suffer a lot in the opening. Gradually and likely, the destination of them always comes to a turning point. So they have to struggle or make some important choices. Then the movie ends up with a happy finale. Or at least the hero finally manages to face his poor life with great courage somehow. However, when audience watch movies in the cinema, most of them just follow the story. Few of them may ask, “Will it happen in the real life?”

    Movies are also imitating the real life. Thus a movie, just like a novel, can never be the same as the real life. The setting of a movie is so ideal that we could hardly find it out in reality. The moviemakers just try their best to persuade the audience to believe the story is true. In a word, it is all just make-believe.

    For quite a long time, I think that the adults' world is realistic in the opposite way of the children's cartoon. However, the movies from the adult world turn out to be a made-up thing. At the very moment, I suddenly realize that movies are somewhat of the adult's fairy tales or cartoons.

    To sum up, other than false comfort such as movies and tales, we are more in need of the maturity of mind, so that we can face our lives bravely and correctly.