I'm really confused about the Present Perfect. I've been looking at some books, seen web pages, amd I still can't find proper rules. Each one says different things.
a) Sharon has studied Spanish every week(day/month) so far (for *** years/months). with this construction, its most likely that she will continue to study Spanish every week.
The sentence "Sharon has studied Spanish this week." works perfectly fine. The frequency and adverbs of time just emphasize the sentence.