I would have gone to my cousin’s birthday party last night, but I available.
A. was
B. had not been
C. was not
D. would not be
网友回答
A. was
B. had not been
(答案→)C. was not
D. would not be
解析：句意为：我昨天晚上本来是要去参加我堂弟的生日派对的，但没有抽出空来。由后面but可知应没去为否定，排除A；had done应发生在过去的动作之前（过去之过去）；would no be是不打算去，过去将来时。这里是陈述了过去发生的一件事情，我没时间没有去成，为过去的即成事实，所以应为C。