托业考试

试题来源：托业-高级动词词汇
【单选题】 The crash investigators were unable to ______ why the truck veered onto the lefthand side of the road.
A．access
B．ascend
C．accede
D．ascertain

参考答案：D
网考网解析：
ascertain是与certain相关的动词，表示确认... 查看试题解析出处>>