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题目内容
（云南工商学院-生活英语听说）
[单选题,10分] Years ago we didn’t know this, but recent science ______ that people who don’t sleep well soon get ill.
A.showed
B.has shown
C.will show
D.is showing
A.showed
B.has shown
C.will show
D.is showing
参考答案
