1. She went to school and then she did the exercised --> Before... 2. I (not listen).... the lesson while the teacher (explain)... it to us

1. She went to school and then she did the exercises

--> Before she did the exercises, she had gone to work ( before+ quá khứ đơn, quá khứ hoàn thành )

2. I wasn't listening to the lesson while the teacher was explaining it to us (while+ quá khứ tiếp diễn, quá khứ tiếp diễn )

1, Before she did the exercises, she had gone to school

(Before+vế quá khứ đơn, quá khứ hoàn thành)

2, wasn't listening/ was explaining

(câu này diễn tả hành động quá khứ, mà có while nên cả hai đều là thì quá khứ tiếp diễn)