我国自然资源的最基本特征是[ ]
A.资源丰富,取之不尽,用之不竭
B.总量丰富,人均不足
C.总量贫乏,人均不足
D.总量丰富,人均量多
答案:B
_____ is known to us all is that the 2008 Olympic Games will take place in Beijing. [ ]
A. It
B. What
C. As
D. Which
GGH吹扫装置的行程编码器为什么要选择双通道发送?