The mosaic theory is the idea that an analyst can:（）

A. make investment recommendations on the basis of several pieces of nonpublic information as long as the aggregate information remains nonmaterial.

B. base his recommendations on nonpublic material information only for the clients of the company, but not for the general public.

C. make recommendations or trade based on several pieces of public or nonpublic information, each piece by itself being nonmaterial, but when compiled the information becomes material.

螺旋机构传动精度高，工作平稳（）易自锁，能传递较大扭矩。

A、易冲击

B、速度高

C、无噪音

D、效率高