具有中枢和外周双重作用的镇咳药是
A．甲基吗啡B．右美沙芬C．溴己新D．苯佐那酯E．咳快好
参考答案：A
ff an investor bought a stock for $ 32 and sold it one year later for $ 37.50 after receiving $ 2 in dividends, what was the holding period return on this investment（）
A. 6.25%.
B. 17.19%.
C. 23.44%.
下列不属于提单的主要作用的是_______。 ( )
A．物权凭证
B．装船依据
C．货物收据
D．运输合同的证明
