元世祖时，来华的外国人中最著名的是[ ]
A．马可·波罗
B．利玛窦
C．崔致远
D．高尔基
答案：A
She would lend me the money if I promised to ________ within a month.
A．bring it back
B．pay for it
C．pay it back
D．pay it out
氧气为什么要经过水封排入大气？
