A. Phrasal Verb
phrasal verb is an idiom which consists of a verb followed by a preposition, a verb followed by an adverb, or a verb followed by an adverb, followed by a preposition. (http://www.wordpower.ws/grammar/gramch27.html)
A phrasal verb actually have a different meaning from its verb. for example
I ran into an old friend (ran into in this sentence have mean to meet somebody unexpectedly not by any chance the meaning is about an exercise i.e running).
so, because of that, at least we know some of word that we could use every day such as