the sea,___their economies have always been based on ,is suddenly threatening their existence.
问题描述：
the sea,___their economies have always been based on ,is suddenly threatening their existence.
A.on which B .where (CD选项不写了）
我选的是B,还有,难道不是on which =where 这到底是为什么T 求拯救!
打错了！base 后面没有on...
答
那就是A,base后面要有介词on,介词提前,而on后要有宾语,用which.where 哪里不对了？on which 不就是where嘛？在后面的词是状语时用where。base后面缺的不是状语【应该是这样】