All possible means , but nothing can prevent the buildings .
A. has tried; from being pulled down
B. have tried; from pulling down
C. has been tried; from pulling down
D. have been tried; from being pulled down
网友回答
A. has tried; from being pulled down
B. have tried; from pulling down
C. has been tried; from pulling down
(答案→)D. have been tried; from being pulled down
解析：考察主谓一致和prevent的用法。All means谓语动词用复数形式，prevent……from doing sth,阻止……干某事
句意为所有的方法都被尝试过了，但是什么也阻止不了这些建筑物被推倒。