English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.
Sign up to join this community
It is thought that people under 18 should be obligated to full-time study their school subjects.
I wonder whether the above sentence is grammatically correct and natural because usually I see native English speaker use full-time as adjective not adverb like this: Most children in the UK remain in full-time education until they are at least 16 years old.
Full-time can't act naturally as an adverb in this context although you will hear people speaking of the need to study full-time.
To fix your sentence, you need to introduce the phrase their school subjects with a preposition.
....to full-time study of their school subjects.
As soon as you speak of full-time study, your listener anticipates that you are using study as a noun, and to omit the preposition is simply puzzling.
It is possible to use an adverb in the context you propose, such as:
....to intensively study their school subjects
although the adverb fits more naturally at the end of the sentence.
