题干

封开县境内新发现了大型的“钼矿”,金属钼可用于制造火箭、导弹等耐高温温材料。若钼铅矿(PbMoO4)中的铅元素为+2价,则钼元素的化合价为    (    )

A:+2    

B:+3    

C:+4     

D:+6

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答案(点此获取答案解析)

D

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完形填空

    A lot happened to me while I lived on Thirteenth Street. I 1 school at Miss Marie Purkins' School for Little Folks kindergarten which I loved until I broke my leg one day 2  rope. And it wasn't3  a moving rope. One of the rope ends in the playground was tied to a tree, the other end to a swing set. The kids would  4  on one side and take turns running and jumping over it. All the other kids5 the rope.

    But I had no6I was a little short and fat anyway, and I was so slow that I was once the only kid at an Easter egg hunt who didn't get a7egg, not because I couldn't find them but because I couldn't get to them 8enough. On the day I tried to jump rope but I was wearing cowboy boots to school. Like a fool I didn't9the boots to jump. My heel 10  on the rope, so I turned, fell and hurt my leg. I lay in11on the ground for several minutes while Daddy12over from his company to get me.

    I had broken my leg above the knee, and13I was growing so fast, the doctor was 14to put me in a cast up to my hip.  15  he made a hole through my ankle, pushed a stainless steel bar through it. And then he 16 it to a stainless steel horseshoe, and 17 my leg up in the air over my hospital bed. For two months, I had been lying on my 18 feeling both foolish, waiting to return to my19 . I missed my playmates so much.

    After I got out of the hospital, my folks bought me a bicycle,20I never lost my fear of riding without the training wheels. No wonder people say, "Once bitten, twice shy."