单项选择题
A.did he B.didn‘t they C.didn‘t he D.did they
Silk（）by Chinese for thousands of years now.A.has usedB...
单项选择题Silk（）by Chinese for thousands of years now.
A.has used B.has been used C.was used D.is used
By the end of this year, I（）enough money for a holidayA...
单项选择题By the end of this year, I（）enough money for a holiday
A.will save B.will be saving C.will have saved D.will be saved
By next year he（）in New York for five years.A.has worke...
单项选择题By next year he（）in New York for five years.
A.has worked B.has been working C.works D.will have worked
