Question

Why doesn’t Cecily want to study German?

Answer 1

I'm assuming you're reading The Importance of Being Earnest, so I think this quote will help; it answers your question well, I think.
- Miss Prism forcing Cecily to learn German showing substance over style and her Victorian views on life. Cecily doesn't want to do this because she thinks it is plain and she believes "it isn't at all a becoming language" showing her preference of style vs. substance and her want to learn a language which is impressive and stylish, rather than full of meaning. ~page 25

from: http://jedge.wikispaces.com/Decadence+as+seen+through+Act+II