一般过去式与过去进行时的区别

一般过去式与过去进行时的区别
初二学生上学期学了一般过去式,上周又学了过去进行时,今晚写作文发现他们老将这俩个时代混用,多数学生是在该用一般过去式的时候用进行时表达,作为老师我该如何帮助学生理解他们的区别呢
学生的病句：
1.I was not sleeping until 14:00 .
2.At 14:00,i was buying a very interesting book.It cost me ten yuan.
3.I was getting up at 6:30 and i was going to school at 7:00.The first class was English.I was feeling very interesting and i was listening to the teacher carefully.