(1) think back指“回想起，忆起”，常与介词on/to连用。

• That song makes me think back to my college days.
  那首歌使我回想起我的大学生活。
• If you think back on the year, you can see what great changes you have made.
  如果你回头想想这一年走过的路，你能看出自己发生了何等的变化。
• Thinking back , it must have happened before the war.
  回头想想，那一定发生在战前。

 (2) ①look back意为“回头看，回顾，回想”，常与介词on/to连用，有时可与think back互换。

• Looking back the way we had come, we could see the whole valley spread out behind us.
  望我们走过的路，可以看到整个山谷在我们身后舒展开去。
• I like to look back on/to my school days, which, though very hard, were among the happiest in my life.
  我喜欢回忆我的学生时代，尽管艰苦，但也是我一生中最快乐的日子之一。
• Looking/Thinking back on it, one realizes that it was far from being a satisfactory conference.
  回想一下，你可以意识到这次大会远不是一次令人满意的会议。
• Never look back , you can't relive the past.
  永远不要回头看，你不能重回到过去生活。

②look back用在否定句中(与not或never连用)，作“不回头，继续前进”解。

• Since Jim got started in business, he hasn't looked back .
  吉姆自从踏进商海，就头也不回地往前走。