对一个公司的收益性进行分析，主要考虑下面一些指标：（）

A.销售利润率

B.投资盈利率

C.资金周转率

D.利息支付能力

How should you signal the crane operator to move slowly?（）.

A.Use one hand to give any miotion signal , and place the other hand motionless in front of the hand giving the motion signal 

B.Extend arm with the thumb pointing up , and flex the fingers in and out for as long as the load movement is desired

C.First tap your elbow with one hand , and then proceed to use regular signals

D.First tap the top of your head with your first , and then proceed to use regular signals