掘进机履带无裂纹,松驰度为()mm。
A、30-50mm
B、25-50mm
C、30-60mm
参考答案:A
The happiest people don't have the best of everything. They just _______ everything. [ ]
A. get away from
B. make the best of
C. fix attention on
D. catch up with
能量既不能消灭,也不会产生,只能从一种能量()为另一种能量。
A、转换
B、转变
C、变化
D、传递