问题

Lisa, now stop for a short break. You should know that you _____all the morning. [ ]
A: are working
B: had been working
C: have been working
D: have worked
B: had been working
C: have been working
D: have worked
正确答案是:
同类题型
Wait a moment, I have _______ to tell you.
_________no doubt that the earthquake is the most serious one in China’s history[ ]
I _____ through the hard time but for my teacher’s generous and timely help.
After two years’ research, we now have a better understanding of the disease
She ’s never been to Japan, ___________—_________. She went there last month.