I don't know that when we use (On,as).please help me... I will wait this question answer....

hi In general, on is used to indicate touching and being supported by the top surface of (something), or moving to a position that is supported by something: The book is lying on the table.There is a lot of frosting on the cake.I climbed out on the roof. As As is a conjunction and an adverb and is used before a clause, another adverb or a clause beginning with a preposition:She enjoys all kinds of music, as I do.