All possible means ，but not a means an obvious effect。
A: have been tried; has
B: have tried; has
C: has been tried; have
D: have been tried; have
A: have been tried; has
B: have tried; has
C: has been tried; have
D: have been tried; have
举一反三
- Every means ______ tried, but in vain. A: have been B: has been C: are D: is
- All possible means __________ been tired.Every possible means __________ been tired. A: have，has B: has，has C: have，have D: has，have
- Every possible means ______. A: has tried B: has been tried C: was tried D: were tried
- If I __________so immature, I would have appreciated all that my family tried to do for me when I was in school. A: bad been B: has been C: hadn't been
- Neither of the young men who had tried to get the job in the company ______. A: was accepted B: were accepting C: has been accepted D: have been accepted