A female swimmer with goggles and a cap does the backstroke .
a female swimmer is training the backstroke for the olympics
A female swimmer with goggles and a cap does the backstroke.
a female swimmer is training the backstroke for the olympics
a female swimmer  is doing the backstroke , she may be training for the Olympics , she may not .
a female swimmer is doing the backstroke , she may be training for the Olympics , she may not .