1 The stident was running to move the bag of rice ( )he heard th sound of a bike.
问题描述：
1 The stident was running to move the bag of rice ( )he heard th sound of a bike.
2 What was your father doing ()your mother was cooking in the kitchen.第一题为什么用when不用while.第二题为什么用while 不用when?
答
while后面一定是进行时,when是过去式,我们老师是这么讲的.