—How about your travel? —You can hardly imagine what difficulty we have had the vast dese

问题补充：

—How about your travel?

—You can hardly imagine what difficulty we have had the vast desert.

A. explored

B. exploring

C. to explore

D. explore

答案：

A. explored

(答案→)B. exploring

C. to explore

D. explore

解析：考查短语：have difficulty（in ）doing sth 做什么事情有困难.句意：你的旅行怎么样呀？你几乎不能想象出我们在探索大草原时有多么的困难。