be a great (big) help (对某人）产生巨大的帮助

　　Thanks. You've been a great help. 谢谢，你给了我巨大的帮助。

　　He was a big help to us, as always. 他对我们帮助很大，每次都是。

　　You're a big help. I think I can't live without you. 非常感谢，我不敢想象没了你应该怎么活。

　　Thank you. You've been very helpful. 很感谢，你给了我巨大的帮助。

　　I see there is a new secretary in the office.  我看见办公室里来了一位新秘书。

　　Yes, she is a great help to all of us.  恩，她对我们帮助很大。