When I wrote down "Thanks for your arduous help", I thought I've chosen the proper word to convey the correct meaning, unrealized of the problem until it was pointed out to me:
arduous is the wrong word; I think you mean extensive or comprehensive (or possibly detailed) in this case. They are similar, but arduous would be used for the process of producing help, not for the help-output.
Yes, I did mean to express extensive, comprehensive and detailed, but from the translated meaning, none of them mean the same level as arduous. I.e., none of them is as powerful as what I want to express. So,
- Why I can't say "arduous help" in this case? I still want to know that fine difference.
- What are the proper words for this, emphasizing on the "excessive" part? The only thing come to the top of my head is "zealous", but I want avoid it because it is most often used in a negative way. Oh, oh, "tremendous" is one, but that only stressed on the "big help" part, not on the part that the other person went overboard to help me.