_____ it or not, his discovery has created a stir in scientific circles.

A．Believe

B．To believe

C．Believing

D．Believed

变速箱使用双副轴的目的是（）

A.使传递的扭力容量加大

B.可防止跳檔

C.使变速容易

D.使变速箱齿轮较不易损坏