study for long hours/study long hours

I would phrase it differently. The problem is that you cannot have "short" or "long" hours. An hour is a set length (60 minutes). So (for example):

I have to study for several hours.
I have to spend a long time studying.

I hope this helps.

Thank you very much for the reply, Dr D. I found the sentence, "I have to study long hours", in my ESL textbook by Oxford University Press. And I wanted to know if you don't need the word "for" before "long hours". But don't you hear anyone saying "long hours" in your place?

Maki

No, their example is bad. You can only use "long" in reference to "hours" if you are speaking metaphorically.
The hours seem long when you have to study. (They aren't actually any longer, but they feel long).

If you say something like:
I studied long days and nights
You are saying something about how time felt to you.
In that case, I would drop the "

Thank you so much, Dr. D!

Maki

Doctor D The problem is that you cannot have "short" or "long" hours. An hour is a set length (60 minutes).

I disagree. 'Long hours' in the sense of 'a long time' is fairly common - there are 1,591 citations in the Corpus of Contemporary American English. Many junior doctors complain about the long hours they have to work.

Thank you for the reply, fivejedjon. So, do you say "I have to study long hours"? And if so, do you also say "for long hours"?

Thank you.

MakiasanSo, do you say "I have to study long hours"? And if so, do you also say "for long hours"?

We more normally work long hours than study long hours, so neither sounds particularly natural to me.

When using the expression "work long hours," the "long" is a colloquial substitute for "many."
They are not saying that the hours themselves are "long." They are saying that the work is "long" (it takes many hours).

Thank you teachers!

Maki