How is the sentence below a fragment? is it missing a subject or predicate. 1. because i know you studied.

I think it is missing the subject. You don't know what the person got as a "reward" for studying. We need a beginning like, "You got a good grade on your test, because I know you study?" See? Anyways, I hope this helps. c;

how do i ask for more info? ?

type of error:

the error in the sentence is a "dangling modifier". a dangling modifier is a phrase, word or clause that "dangles" because there is not target to modify. in this case, "after mopping the floor" is the dangling modifier since it has no word to modify. the noun "house" cannot mop the floor; therefore there is a mistake in the writing of the sentence.