4. We ________ on it for several hours but we have not yet reached any conclusion.
A: A. work
B: B. are working
C: C. have been working
D: D. have been worked
A: A. work
B: B. are working
C: C. have been working
D: D. have been worked
举一反三
- We ______ on it for many hours, but we have not yet reached any conclusion. A: are being worked B: are working C: have been working D: have been worked
- We（）on it for many hours but we have not yet reached any concinsion. A: work B: have been worked C: have been working D: are working
- We ________ on it for several hours but we have not yet reached any conclusion.
- By the end of next month I ______ here for five years. A: will work B: have been working C: have worked D: will have been working
- I____(work) as an assistant manager for four years. A: work B: have worked C: am working D: have been working