He could have finished it on but he was ill last week and that was why he fell behind.A.

问题补充：

He could have finished it on , but he was ill last week and that was why he fell behind.

A. schedule

B. disadvantage

C. purpose

D. timetable

答案：

(答案→)A. schedule

B. disadvantage

C. purpose

D. timetable

解析：词义辨析。A. 时间表 B.缺点 C.目的 D. 时间表；课程表。句意：他本能按时完成，但是上周他生病了，那是他为什么落后了。短语on schedule，按时，故选A。