That is because the whole messy business involves elements of behavioural psychology as well as the laws of mechanics, control theory and fluid dynamics.
因为该理论牵涉的领域庞杂，包括行为心理学、机械学，控制理论学和液体动力学。
2
During runtime, Slice calls back to this user implementation and USES the returned values to control the flow. The available policy mechanics are.
在运行时期间，Slice回调至用户实现并使用所返回的值来控制流程。
3
Composite wing design, in which involved are many disciplines such as structural mechanics, aerodynamics and control engineering, is a complicated process.