As a conductor, Leonard Bernstein is famous for his intensely vigorous and exuberant style.

A．enthusiastic

B．nervous

C．painful

D．extreme

（）不是造成链条、链轮故障的原因。

A.传动链条、链轮磨损严重

B.离合器打滑

C.缓冲壳体轴承、轴套磨损

D.链轮固定螺栓松动