吹灰器吹灰也可能反而引起管子腐蚀或刷蚀，其原因不包括（）。
A．吹灰气体中有凝水
B．吹灰次数过于频繁
C．气流速度过高
D．气流温度过高
参考答案：D
A．2g氢气所含的原子数为NA
B．1mol氢气所占的体积约为22.4L
C．1mol氢气的质量是2g/mol
D．H2的摩尔质量是2g•mol-1
An analyst does research about capital structure. The optimal capital structure for a company is best described as the capital structure to maximize that company's:（）
A. stock price.
B. earnings per share.
C. dividends per share.
