—Do you know the colors of the Olympic rings?

—Yes. They're blue, yellow, black, green and red. You can find ____ one of these colors in the flags

    of every country. [ ]

A. at least

B. at most

C. only

D. more than

曲轴是一个形状复杂、刚度差的零件。在车削加工时，为了减小曲轴的弯曲和扭转变形，可采用（）传动或（）传动方式进行加工，并尽量采用有前后刀架的机床使加工过程中产生的（）互相抵消。