---Where was your sister at this time yesterday evening ?
---She was writing an e-mail I was watching TV at home.
A. after
B. as soon as
C. while
D. until
网友回答
A. after
B. as soon as
(答案→)C. while
D. until
解析：after在……之后；as soon as 一……就……；while当……时，强调两个动作同时发生；until直到，常和not搭配使用。结合上文可知下文句意为：当我在家看电视时，她正在写电子邮件。故选C。