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?

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?