I really appreciate it.

　　我很感谢。

　　Youre one in a million.

　　你真是个大好人。

　　Youre the greatest.

　　你最棒了。

　　Thanks to you (we made it on time.)

　　都要多谢你(我们才能准时完成)。

　　I couldnt have done it without you.

　　若是没有你，我不可能做到。

　　Im truly grateful for your help.

　　我非常感激你的帮助。

　　Your help is greatly appreciated.

　　非常感激您的帮助。 (很正式!)

　　Id like to express my gratitude.

　　我要表达我诚挚的谢意。 (相当正式!)