Question

He ________ his homework at 9 o’clock yesterday .
A. does       B. was doing      C. did

Answer 1

B

do one’s homework是固定短語(yǔ)，因其主語(yǔ)是he，第三人稱單數(shù)故其謂語(yǔ)動(dòng)詞要用第三人稱單數(shù)。