---Where was your sister at this time yesterday evening ?---She was writing an e-mail I w

问题补充：

---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

答案：

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。