When he learned of his failure, George thought of [color=blue]quitting school. But after sober consideration, he realized that would be unwise.
Source: vocabulary for the High School Student Robert T.Levine
Isn’t it incorrect of the author has not used the article ‘the’ or a possessive adjective ‘his’?
I mean why no article ‘the’ or possessive adjective ‘his’ are used before the word ‘school’?
I think the best way to put it is: “dropping out of school” (i.e. you quit school before you have a chance to graduate and get a diploma).
You usually quit a job, not school.
That said, you don’t need an article/determiner (a, the, his) if you’re thinking of school in general (i.e. you’re not referring to a particular school/school building)
In your case “school” is more like an activity:
I can’t stay up late because I have school tomorrow.
Right. In this case, if you say ‘quit the school’ or ‘quit his school’, it suggests just one particular school. In other words, he might have decided he didn’t like that one particular school and decided to attend a different school instead.
But if you say ‘quit school’, then that suggests he decided to stop receiving an education. In other words, he stopped going to his school and had no intention of going to any other school either.