肾性急性肾衰竭的临床特点中下列哪项不存在（）
A.少尿
B.无尿
C.尿钠浓度降低
D.等渗尿
E.管型尿
参考答案：C
—Thanks a lot, Mr. Wang. I don't know how to ________ the help you gave me during my stay here.
—It's my pleasure. Welcome to China again when you have time. [ ]
A. pay off
B. pay back
C. pay for
D. pay to
会展市场调研过程的开始首先是（）。
A.确定调研目标
B.认识营销问题或机会
C.设计调研方案
D.设计调研计划
