什么是溴价？
参考答案：
100克油品中所含的不饱和烃通过加成反应，全部变成饱和烃所需的溴的克数称为溴价。
She had almost failed the exam, but her sister, ________had done very well.[ ]
A. contrast with
B. contrasting with
C. by contrast
D. by difference
集装箱货物常用交接方式有( )。
A．门到门交接
B．门到场或站交接
C．场到场交接
D．站到站交接
