英语翻译演出还没结束孩子们就睡着了(before)Children fell asleep before the performance has finished.

The children had slept before the performance finished

The performance was not over the children went to sleep

The children was asleep before the performance finished.

Children had fell asleep before the show finished

不对,before之前是先发生的,应该用过去完成时
Children had fallen asleep before the performance has finished.

Children had fallen asleep before the performance ended.