根据我国现行的包裹资费标准，保价费按保价金额的( )计算。
A．1%
B．2%
C．5%
D．10%
参考答案：A
If we don’t prevent some students from surfing the Internet late at night, they won’t do their homework on time, ________.
A．or rather
B．or worse
C．or so
D．or more
天然气的爆炸极限是多少？
