一I still cannot figure out why he missed his flight．

一He       an accident on the way to the airport．

A．could have had

B．should have had

C．would haye had

D．must have had

著名的霍桑研究就是采用（）研究管理中人际关系的成功例子。

A.归纳法

B.试验法

C.演绎法