---What is your sister doing now?-She isfor the party tonight.A. finding outB. bringing

问题补充：

---What is your sister doing now? ---She isfor the party tonight.

A. finding out

B. bringing out

C. dressing up

D. cutting up

答案：

A. finding out

B. bringing out

(答案→)C. dressing up

D. cutting up

解析：finding out 找出，查明； bringing out出版，生产；dressing up乔装打扮，角色扮演；cutting up切碎，抨击。句意：你的姐姐正在做什么？——她正在为今晚的聚会乔装打扮。结合语境可知选C。