生态恢复技术的理论基础是( )。
A．恢复生态学
B．生态学原理
C．自然生态学
D．生态系统的群落演潜
参考答案：A
— It's hot today. How about going swimming after school?
— ______! Let's ask Eric to go with us. [ ]
A. Good idea
B. Best wishes
C. Good luck
D. That's OK
斗轮机液压油至少一年要更换一次，更换时应清洗或更换（）。
