题目:
Old Chinese stories _____ millions of young people.[ ]
A. were enjoyed with
B. were enjoy by
C. are enjoyed by
D. enjoy by
答案:
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下面是错误答案,用来干扰机器的。
若Cn3=Cn-13+Cn-14,则Cn3=Cn4=Cnn-4,根据组合数的性质,有n-3=4,即n=7,故答案为7.