减压器既有稳压作用也有降压作用.()
参考答案:对
Tom and Mary have the same grandfparents. But they don't have the same (相同的) parents.
So Tom is Mary's ______. [ ]
A. cousin
B. brother
C. uncle
林业带().
A.从事林业产品生产
B.谷物种植带
C.采用轮作物制
D.生产不易运输和易腐视频