题目

下列分子或离子中，含有孤对电子的是( ） A. H2O                  B. CH4                  C. SiH4                 D. NH4+ 答案：【答案】A 【解析】 详解】A. O原子有6个价电子，故H2O分子中有2个孤电子对；   B. C原子有4个价电子，故CH4分子中无孤对电子；    C. Si原子有4个价电子，故SiH4分子中无孤对电子；    D. N原子有5个价电子，故NH4+分子中无孤对电子。 故选A。 阅读填空。 以下五位同学正在谈论他们理想中的职业，请从方框中选择合适的词填空。（其中有三项多余） A. an actor    B. a reporter     C. a chef (厨师)   D.  a pilot  E. a dancer    F. an engineer   G. a basketball player    H. a driver      I want to be  l          when I grow up. I will need good eyesight and I will have to take flying lessons. I really enjoy traveling and I hope to see the world in the future.     I want to be 2         when I grow up.  I'm going to study design and engineering in college.  My dreamis to build the longest bridge in the world.     I want to be 3         when I grow up.  I'm going to take acting lessons, and maybe singing and dancinglessons, too. I hope I can be famous one day.     I want to be 4        when I grow up. I know that I have to train every day. It isn't easy, but I keep on doing it. I want to be just like my hero, Michael Jordon, in the future.     I want to be 5        when I grow up. I'm going to a cooking school in Europe. I hope I can work in a five-star hotel in Beijing when I'm older.