第1个回答 2010-04-14
1.The students(they) were doing their homework when the teacher came in the classyoom.
2.While the students(they) were doing their homework,the teacher came in.
一般有两种说法的。
第2个回答 2010-04-14
They were doing their homework when the teacher came into the classroom.
第3个回答 2010-04-14
They are doing homework when the teacher comes in the classroom
第4个回答 2010-04-14
They were doing their work when the teacher walked into the classroom.