He the job well, but he so careless.
A. had done; had been
B. could do; was
C. could have done; was
D. hadn’t done; had been
网友回答
A. had done; had been
B. could do; was
(答案→)C. could have done; was
D. hadn’t done; had been
解析：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。”