问题
选择题
The number of historic buildings which ________ has reached a surprising figure that we must be aware of.
A．has been pulled down
B．had been pulled down
C．is being pulled down
D．have been pulled down
答案
答案：D
选D 考查时态和主谓一致。句意：我们必须意识到，已被拆毁的历史建筑的数量惊人。主语部分含有一个which引导的定语从句，先行词是buildings，因此从句中的谓语应该用复数形式。再根据句意可知，此处用现在完成时，表示“已经被拆毁的”。