Student or Learner
I am not sure whether or not I need a preposition in the examples below.
(1) You can write English or write in English.
(2) You can read English or read in English.
Please explain it. Thanks.
You can write English means "you know how to write in English." You can write in English means "you have permission to write in English." (Some grammarians would prefer the verb may, but "can" means the same thing to nearly every Anglophone in this usage.)
For sentence 2, only the first option is possible. It means "you know how to read English." You could say You can read it in English in a context like "here's a text in both English and Hebrew versions. You can read it in English."
I am not a teacher.