题干

使用如图所示装置进行实验,开始前气球沉在烧杯底部,过一会儿气球悬浮在烧杯内(气球本身质量忽略)下列对气球内充的气体的分析中不正确的是(   )

A:氢气

B:氮气

C:空气

D:氧气

上一题 下一题 0.0难度 选择题 更新时间:2017-08-29 02:34:44

答案(点此获取答案解析)

A

同类题4

阅读下面短文,从短文后各题所给的四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

    After thirty years in the classroom, I have come to realize that teacher's behavior can make a world of difference for a child. This is one such 1.

    While I was attending a party being 2 at a high school one evening, I looked around and noticed a young girl who looked 3. I thought she had been a(n) 4 of mine. I tried to remember her 5, but I couldn't. I felt so frustrated (沮丧的), 6 I have always been able to 7 former students.

    Her eyes met mine and she threw her 8 around me and said, “Mrs. G, it's me, Sarah, and I'm still 9!” The memories 10. You see, Sarah was 11 a student in my classroom. Sarah's mother had abandoned (遗弃) her, and her father had 12 her. She was sent to live with her grandparents the year I 13 her. Sarah was angry, often in 14 and often in the office.

    It was during one of those 15 visits that I first met her. She was writing. I introduced myself to her and asked her 16 she was writing. Sarah shared her story with me. I knew it was healing (康复) for her to put her 17 on paper. Every morning before school she would come into my classroom and we would work on her writing skills.

    Our conversation that evening was filled with 18. She expected to go to college. Driving home, I could not help but 19 the impact (影响) for both good and bad that teachers have upon their students. Taking the time to 20 with a child has the power to change that child's life. That's why I teach.

同类题5

阅读下面的文章,完成文后题目。
老 王
      有一天,我在家听到打门,开门看见老王直僵僵地镶嵌在门框里。往常他坐在蹬三轮的座上,或抱着冰伛着身子进我家来,不显得那么高。也许他平时不那么瘦,也不那么直僵僵的。他面如死灰,两只眼上都结着一层,分不清哪一只瞎,哪一只不瞎。说得可笑些,他简直像棺材里倒出来的,就像我想像里的僵尸,骷髅上绷着一层枯黄的干皮,打上一棍就会散成一堆白骨。我吃惊地说:“啊呀,老王,你好些了吗?”
       他“嗯”了一声,直着脚往里走,对我伸出两手。他一手提着个瓶子,一手提着一包东西。
        我忙去接。瓶子里是香油,包裹里是鸡蛋。我记不清是十个还是二十个,因为在我记忆里多得数不完。我也记不起他是怎么说的,反正意思很明白,那是他送我们的。
        我强笑说:“老王,这么新鲜的大鸡蛋,都给我们吃?”
         他只说:“我不吃。”
       我谢了他的好香油,谢了他的大鸡蛋,然后转身进屋去。他赶忙止住我说:“我不是要钱。”
      我也赶忙解释:“我知道,我知道不过你既然来了,就免得托人捎了。”
    他也许觉得我这话有理,站着等我。
    我把他包鸡蛋的一方灰不灰、蓝不蓝的方格子破布叠好还他。他一手拿着布,一手攥着钱,滞笨地转过身子。我忙去给他开了门,站在楼梯口,看他直着脚一级一级下楼去,直担心他半楼梯摔倒。等到听不见脚步声,我回屋才感到抱歉,没请他坐坐喝口茶水。可是我害怕得糊涂了。那直僵僵的身体好像不能坐,稍一弯曲就会散成一堆骨头。我不能想像他是怎么回家的。