Seeing their teacher ( )(walk)into the classroom,theystopped talk_英语解答

Seeing their teacher ( )(walk)into the classroom,they
stopped talking at once.
walk不是一个瞬间动词吗,为什么答案上写的是walking?

人气：337 ℃　时间：2019-10-23 02:50:26

解答

see sb.doing sth.看见某人正在做某事,固定表达,所以填写“walking”