look back
1．review the past ； think of what has happened回顾过去；回想
If we look back， we will realize the tremendous changes reform has made．回顾过去，我们就会发现改革带来的巨大变化。
He looked back with remorse on the serious mistakes he had made．他回顾自己所犯的严重错误，深感悔恨。
As John looked back，his life seemed good to him．约翰回顾过去的生活时，他觉得过得不错。
2． show signs of retrogression or interrupted progress后退；停止不前；畏缩
Don't look back； you will succeed．不要畏缩，你一定会成功的。