对于n个元素的关键字序列{k1，k2，…，kn}，当且仅当满足关系ki≤k2i，且ki≤k2i+1（2i≤n，2i+1≤n）称其为小根堆，反之则为大根堆。以下序列中，（）不符合堆的定义。

A．(4,10,15,72,39,23,18)

B．(58,27,36,12,8,23,9)

C．(4,10,18,72,39,23,15)

D．(58,36,27,12,8,23,9)

The first two questions were easy; but the rest of them ____ not.[ ]

A. was

B. were

C. being

D. to be