在某个草原生态系统中，能正确表示草、兔、鹰三种生物数量大小的图示是 [ ]
A.
答案：D
OH5000等无齿轮电梯更换变频器或主机编码器移位、拆装、更换，都必需进行（），电梯才能运行。
一It's said that aliens tried to warn the astronauts on the moon to _____.
一Maybe they didn't like human beings to get close to them.[ ]
A.stay up
B.stay out
C. stay away
D.stay behind
