Our teacher is always busy preparing lessons until 11 o'clock at night,____Our teacher is always busy preparing lessons until 11 o'clock at night,______ we students have gone to sleep.A.that time B.by which time C.by that time D.which time

来源:学生作业学帮网 编辑:学帮网 时间:2024/05/28 11:39:58

Our teacher is always busy preparing lessons until 11 o'clock at night,____
Our teacher is always busy preparing lessons until 11 o'clock at night,______ we students have gone to sleep.
A.that time B.by which time C.by that time D.which time

B have done 是完成时态 by the time 非限从 the 改为 which