A. is; are B. are; is C. is; is D. are; are
单项选择题This machine, （）for many years, is still working perfectly.
A. after which I have looked B. which I have looked after C. that I have looked after D. I have looked after
单项选择题I have no doubt （）we shall be able to do something for you.
A. whether B. if C. that D. what
