单选题 I would (have come) to see you (had it been) possible, but I (had been) so busy (then).

A、 have come
B、 had it been
C、 had been
D、 then

【正确答案】 C

【答案解析】将had been改为was。注意前半句的特殊句式。正常的句式应该是“I would have come to see you if it had been possible”，省略条件句的标志词if时，条件句要倒装。虚拟语气的结构已经在前半句中得到了完整体现，因此后半句只用一般过去时即可。