英语独立主格题目________,all the students ran out of the classroom.A

英语独立主格题目
________,all the students ran out of the classroom.
A.Class was over B.Class is over
C.Class over D.When class over
.________,Mother had to stay at home and looked after him.
A.Being ill B.He was ill
C.Tom being ill D.To be ill
为什么一个要加being 一个不用