— Thank you for the great trouble you have taken _____ me with my English?

— Think nothing of it! [ ]

A. with helping

B. to help

C. in helping

D. helping

反铲挖掘机连贯操作则是将挖土、升大臂、旋转、卸土、同转和降大臂六个基本动作进行复合。以下可复合的动作是（）。

A.挖土和升大臂

B.提升大臂和旋转

C.旋转和卸土

D.卸土和回转