I have __________ the problem for two ho
题型:选择题
问题:
I have __________ the problem for two hours, but I haven't __________.[ ]
A. worked on, worked out it
B. worked at, worked it out
C. worked on, worked it out
I have __________ the problem for two hours, but I haven't __________.[ ]
A. worked on, worked out it
B. worked at, worked it out
C. worked on, worked it out