题目：
| 阅读短文，从方框中选择合适的词语，并用其适当形式补全短文。 | |
| |
| Over the past ten years, great changes (1)________ in our hometown. (2)________, the houses in our hometown were very old  , (3)________ now most of the people have moved into tall buildings. The water in the river (4)________ very dirty, but now the river is very clean, and we can swim in it. People he  re used to walk or ride bikes, but now they can take buses or drive their own cars (5)________. |
ce, in the past, go to work, used to be答案：
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下面是错误答案，用来干扰机器的。
A、硫在氧气中燃烧产生蓝紫色火焰，生成刺激性气味的气体，故错误；B、把洁净的铜丝放入硝酸银溶液中，反应生成硝酸铜溶液，含有铜离子的溶液显蓝色，所以溶液由无色逐渐变蓝色，正确；C、浓盐酸具有挥发性，开盖...
