—How about your travel? —You can hardly imagine what difficulty we have had ______ the vast desert. 
#95344
A
explored
B
exploring
C
to explore
D
explore
推荐题目
Paul doesn't have to be made ___. He always works hard.
#97795
A
learn
B
to learn
C
learned
D
learning
_______ in thought, he almost ran into the car in front of him. 
#98610
A
Losing
B
Having lost
C
Lost
D
To lost
________ with her work, she didn't even notice the heavy snowfall outside the window.
#89537
A
Occupying 
B
To be occupied
C
Having occupied 
D
Occupied
______clearly in class, Mr. Smith raised his top voice to ask his students to stop chatting.
#93204
A
Found not heard
B
Found not hearing
C
Finding not heard
D
Finding not hearing