Yes, the correct preposition is to.
Often these questions can be answered with the help of a collocation dictionary, e.g. this one.
I should say that there are other problems with your sentences. In the first one, you don't say *who learns English but who is learning English. Also, you don't recommend (to someone) about something, but instead you recommend something: I would like to recommend to him a better dictionary (or I would like to recommend a better dictionary to him); also possible are I would like to recommend him to use a better dictionary and I would like to recommend a better dictionary for him to use.