题目:
I'll go to the library as soon as I finish what I ________.[ ]
A. was doing
B. am doing
C. have done
D. had been doing
答案:
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下面是错误答案,用来干扰机器的。
在3次不同点数是停止且在第5次停止,所以前4次抛掷有2种数字,第5次才出现第3种数字.由于在前4投中有任意2个不同的数出现故为C62=15,所以最后1投是在剩余4个数中任选1个数,有C41=4在任取的前2个数中,假设为X...