Jim, look _____ the photo of my sister, Lily. [ ]
A. to
B. at
C. in
D. is
答案:B
每小时将20kmol含乙醇40%的酒精水溶液进行精馏,要求馏出液中含乙醇89%,残液中含乙醇不大于4%(以上均为摩尔分数),试求每小时馏出液量和残液量(10分)
简述公共部门绩效评估的特征。