It was the second-hand bus that the mechanic spent the whole afternoon in the factory.A.

问题补充：

It was the second-hand bus that the mechanic spent the whole afternoon in the factory.

A. in repair

B. repaired

C. repairing

D. to repair

答案：

A. in repair

B. repaired

(答案→)C. repairing

D. to repair

解析：考查强调句型。被强调部分为spent的宾语而宾语要由名词、代词、动名词等充当所以要选C. repairing。修理工花费了整个下午在厂子里修理这辆二手车。