问题
Pollution is a serious problem. Scientists have _____ some good ways to save it.
A:as big as
B:as older as
C:as old as
D:so old as;
B:as older as
C:as old as
D:so old as;
正确答案是：
同类题型
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ing_____ gift they wanted, the kids screamedwith _____ delight.
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