NOT A TEACHER
(1) I think that perhaps that you are referring to so-called phrasal verbs. (Verbs with two or more words.)
(2) I think that native speakers use them when they do not want to be too formal:
(a) For example, I got on the bus. (Formal: I boarded the bus.)
(b) I got off the bus. (Formal: I alighted from the bus.)
(c) I took Mona in to dinner. (Formal: I escorted Mona to dinner.)
(d) Take off your sweater. (Formal: Remove your sweater.)
(e) Shut up! (Formal: Refrain from speaking!)
(3) Sometimes native speakers use phrasal verbs because they sound more natural
(If you said "I alighted from the bus," many people would laugh); sometimes there may
not be a really good "formal" word to express the idea; if you are writing something for
a university class, however, you might want to use formal words whenever possible.
(4) When you get time, use the search box at this helpline for "phrasal verbs." Mr.
Paris, the teacher, has already given us a helpful link. I also guess that the Web
has many results. Just google "phrasal verbs."
(5) I know that it is very difficult, but don't give up (surrender). Just keep on
(continue) studying, and one day very soon you will catch on (understand)!
