[求助] 885-A-15

              Since 1975 the number of women in upper-level management in American corporations have increased by 25 percent; female executives’ salaries, however, still lag behind those of their male counterparts.

(A) have increased by 25 percent; female executives’ salaries, however, still lag

(B) has increased by 25 percent, however much their salaries lag

(C) have increased 25 percent; female executives’ salaries, however, still have lagged

(D) has increased by 25 percent; female executives’ salaries, however, still lag（D）

(E) have increased 25 percent; their salaries, however, still lag

since....+ ; 有没有问题啊?  正确地用法是不是应该是 Since.... , .....

up