"She swims perfectly."
Translation:Zij zwemt perfect.
Volstrekt means completely or unlimited but can only be used to 'enlarge' something (similar to very in English), e.g.:
- dat is volstrekt belachelijk = that is completely ridiculous
- ik geef je volstrekt gelijk = you are completely right [lit: I give you completely right]
I'm not sure, but it could be that you're mistaken volstrekt for volmaakt which does mean perfect and can be used in this sentence.