Question

He ____the job well, but he_______so careless.

1. A.
   had done; had been
2. B.
   could do; was
3. C.
   could have done; was
4. D.
   hadn’t done; had been

Answer 1

C
答题的关键在于抓住句中的but，but后面的句子是对过去事实的陈述，应用一般过去时；前面的句子则表示“本来能够……”，是对过去事情的推断，因此应用could have done，句意为“他本来能够做好那工作，但他太粗心了。”