AG3 - units 16 and 17

There is a difference between Adverb phrase and adverbial phrase

I think is more easy

I do all the housework whereas my husband is watching Pokemon.

I study grammar because is necessary.

I can play different musical instruments. Even I play the drums

Adverbs can be words, clauses and phrases

I think it's much easier

When you make adverb phrases of reason, they should be present in the sentence.

I really like grammar although is hard

Which sentence is correct?