"My sister is paying."

Translation: Meine Schwester bezahlt.

[phle]

What is the difference between "zahlen" and "bezahlen"?

[pnique]

Isn't an umlaut missing

[nicofs]

Don't confuse "zahlen" (to pay) and "zählen" (to count)... ;-)

[wataya]

The German sentence is fine.

[dperseo]

yeah, but the exercise marks as correct both sentences: 1.- Meine Schwester bezahlt; and 2.- Meine Schwester zahlt. So, the point of -phle,(as me too) is when is used one sentence and when the other one?