Although women’s wages are improving, Department of Labor statistics show that the ratio of their earnings with that of men have been roughly static since 1960.
A: with that of men have been
B: to that of men are
C: to those of men have been
D: with those of men is
E: to those of men has been 我选的C,答案是E 。这个明明是复数,为什么选has been ,而不选have been呢