题目内容
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
答案:B
解析:
解析:
|
根据 but表示的转折意义判断,后面应说明现在的情况,与几年前相对照,并且空后说明了结果,所以应用现在完成时。 |
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