Jack borrowed the tie ______ his father. [ ]
A. to
B. of
C. from
D. by
答案：C
依据产品用途，将天然气中C3以上轻烃组分加以回收，一般只需冷冻至（）℃，即可满足回收工艺条件，通常称这种冷冻深度为浅冷分离。
A.-10~-12
B.-15~-18
C.-20~-25
D.-30~-35
为什么要用汽轮机高压内缸内壁上部温度150℃来划分机组的冷、热态启动？
