问题
选择题
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
答案：B
考查动词的时态。根据句子中的recent science可以知道句子中“含有过去发生的动作”对现在产生的影响。所以答案应该用现在完成时。