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