The doctor spent nine hours ________ on the eye of the wounded soldier.
The doctor spent nine hours ________ on the eye of the wounded soldier.
A.to operate
B.operating
C.in operating
D.both B and C
答案及解析： B
The doctor spent nine hours ________ on the eye of the wounded soldier.
A.to operate
B.operating
C.in operating
D.both B and C
答案及解析： B