什么叫双流程凝汽器？
参考答案：
同一股冷却水在凝汽器内转向前后两次流经冷却水管的凝汽器称之为双流程凝汽器。
设全集U＝{x∈N*|x<6}，集合A＝{1,3}，B＝{3,5}，则∁U(A∪B)等于________．
—Which one is your little sister?
— The one _____ long hair and big eyes.[ ]
A. in
B. with
C. at
D. on
