Threedaysaftertheaircraftwentmissing,aninternationaleff...

问题详情：

Three days after the aircraft went missing, an international effort ________ ships and planes hasn't found any wreckage, ________ growing frustration for the families of the 239 people on board.

A. involved; causing      B. to involve; caused

C. involving; causing     D. involving; having caused

【回答】

C

知识点：动词

题型：选择题