要将旋转运动转化成平稳又能产生很大轴向力的直线运动可采用（）传动。

A.齿条

B.蜗杆

C.螺旋

D.齿轮

The mariner must be the final judge of the reliance he can place on the information given in the Admiralty charts and other publications,since they（）.

A.may always be complete and up-to-date

B.may not always be complete and up-to-date

C.may sometimes be complete and up-to-date

D.may not sometimes be complete and up-to-date