The following data pertains to a company’s common-sized financial statements. Current assets 40% Total debt 40% Net income 16% Total assets $ 2000 Sales $1500 Total asset turnover ratio0.75 The firm has no preferred stock in its capital structure. The company’ s after-tax return on common equity is :（）

A. 15%.

B. 16%.

C. 20%.

汽轮机启动时为了保证金属部件有一定的温升速度，要求蒸汽温度（）金属温度，且两者相匹配，相差太大就会对金属部件产生（）。