问题描述：
Seeing their teacher ( )(walk)into the classroom,they stopped talking at once.
walk不是一个瞬间动词吗,为什么是walking?
walk不是一个瞬间动词吗,为什么是walking?
问题解答：
我来补答展开全文阅读
问题描述：
问题解答：
我来补答