She is an experienced singer. She feels completely（ ）when singing before a large audience.
A、
for ease
B、
in case
C、
at ease
D、
on case
【正确答案】：C
【题目解析】：
(feel) at ease：感到十分自在，选C。句意：她是一位有经验的歌手。当她在一大群观众面前唱歌时，她感到非常自在。
She is an experienced singer. She feels completely（ ）when singing before a large audience.
She is an experienced singer. She feels completely（ ）when singing before a large audience.
for ease
in case
at ease
on case
(feel) at ease：感到十分自在，选C。句意：她是一位有经验的歌手。当她在一大群观众面前唱歌时，她感到非常自在。