常用的氢系统的冷凝干燥法有两种，一种用于制氢系统干燥法；另一种为用于专门发电机内氢气干燥法。（）
参考答案：对
— I'm sure Andrew will come out first in this gymnastic competition.
— I think so. He ________ for it for months.[ ]
A. is preparing
B. was preparing
C. had been preparing
D. has been preparing
下列各项中，正确的电子邮箱地址是( )。
A．L202@sincom
B．TT202#yahocom
C．A112.256.23.8
D．K201&yahococn
