Answer:
Gretchen has always been very good at math.
With an online dictionary, you don't have to flick through a physical dictionary looking for the word you need-- you just have to type in what you want.
Adverbs are words that are used to modify or qualify the verb, adjective and sometimes another adverb. From the sentence above and from the choices given, the word that is not an adverb is the word because. Thus, the answer is letter D.
