— Did you go to the open-air concert?

— No. We ____. but we spent too much time shopping. [ ]

A. could have gone                  

B. must have gone

C. can't have gone                  

D. shouldn't have gone

对检测方法实用性的要求不包括（）

A.方法简单快速

B.样品和试剂使用微量

C.适合大批量和单份标本检测

D.经济实用

E.量值可溯源准确性高