题目内容：

英语 One-third of the area _______ covered with green trees.
About seventy percent of the
trees _______ been planted.
A.are; have B.is; has C.is; have D.are; has

优质解答

C
因为第一句的主语area是不可数名词,所以用is
第二句的主语trees是可数名词的复数,所以用have.