热对流
参考答案：
指流体各个部分之间发生相对位移，冷热流体相互掺混引起热量传递的方式。
There is an obvious _______ between children spending too much time playing computer games and their bad grades at school.
A．possibility
B．connection
C．chance
D．cause
目标分解所达到的深度应当以( )为原则。
A．能分能合B．远粗近细C．能够取得可靠的数据D．与组织分解结构相对应
