I’ve seen this error often even in intermediate to advance students’ writing. Here’s the difference between ‘most x’ and ‘most of x’
Most, as in:
“Most university students prefer classes that start after 10 a.m.”
Here, the noun “university students” is plural and is used as a general group. No determiner (such as ‘the’) is used after ‘most’.
Most of, as in:
“Most of the students in our dormitory have their first class after 10 a.m.”
Here, the noun “the students” is a specific group – those in our dormitory. So it’s a large portion within a specific group of students. You need to use a determiner (the/my/his/her/your/our/their/) followed by the noun if you use ‘most of…’. For example, “Most of my students have studied English since primary school.”
More examples (you can see the slight difference in meaning):
- According to a nation-wide survey, most employees feel they shouldn’t have to work more than 40 hours per week.
- Most of the employees (at my company) feel they shouldn’t have to work more than 40 hours per week.