( )反映每元成本费用支出所能带来的利润总额。

A．成本费用利润率

B．税前利润率

C．营业利润率

D．销售利润率

Which of the following statements about Langerhans’ cells is TRUE

A．They commonly are found in the dermis

B．They function as sensory mechanoreceptors

C．They function as receptors for cold

D．They play an immunologic role in the skin

E． They are of epithelial origin