问题
I found _________difficult to work out the problem.[ ]
A: it's
B: this
C: that
D: it
B: this
C: that
D: it
正确答案是：
同类题型
Liu Xiang and Yao Ming are famousplayers.____of them have set a good example to us.
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don’t believe what he told us about meeting Yi Zhongtian. I think he was ______ the story.
The matter _______people’s health surely requires ______ carefully.