Why study Prasal Verb and Idiom? How Important are they?

[william_pp_kh]

I very happy to know from you all.

[Tdol]

You could communicate without using them, but it would not sound very natural.  However, more importantly, without a knowledge of basic phrasal verbs and idioms, your comprehension will be greatly reduced.  We use phrasal verbs all the time and are inventing new ones every day, so they are a central part of English.