语法与词汇 29.______the project in time, the staff were working at weekends.
【正确答案】 D
【答案解析】句意：为了及时完成这项工程，全体员工周末一直在工作。由后句the staff were working at weekends可知，在周末一直在工作的目的就是按时完成工程，因此用不定式作目的状语，故答案选D。