We know that English comprises 8 parts of speech. Every one of these parts is important for proper communication between people, both in the written and the spoken form. Three of these parts - the verb, the preposition and the adverb - combine to provide much more meaning to communication. We often come across verbs that are followed by prepositions or adverbs. We find that when these words are taken together the meaning is quite different from what the verb alone conveys.
‘The plane TOOK OFF from the runway.’ This sentence means that the plane has flown off the ground and into the sky. TOOK OFF is known as a phrasal verb and here it comprises TOOK, a verb and OFF, an adverb.
‘I will THINK ABOUT going to high school.’ This is another sentence in which THINK ABOUT is a phrasal verb and here it comprises THINK, a verb and ABOUT, a preposition.