it is normal for parrots to talk, Einstein, a small bird, is unusual in that whenever she hears a new word or sound, she repeats it over and over until she masters it.
A. As
B. When
C. While
D. Since
网友回答
A. As
B. When
C. While
D. Since
解析：选C。考查状语从句。句意: 尽管鹦鹉说话是正常的, Einstein, 一只小鸟, 是非同寻常的, 因为每当她听见一个新单词或者声音的时候, 她总是重复说直到掌握。while尽管; as因为; when当……的时候; since既然。