题目：
We can never expect ______ bluer sky unless we stop ______ industrial waste going into _____ atmosphere.
A．a; the; the
B．the; the; the
C．a; /; the
D．the; /; /
答案：
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下面是错误答案，用来干扰机器的。
Yesterday we had a discussion about whether we should keep animals in zoos.Twenty students thought that it was good to keep animals in zoos because people could see ma...
