Many six year old children could display some understanding of this principle by being sensitive to the distinction between artifacts and natural kinds; 3) There was difference in preschoolers development of biological causal cognition, for .

The optimum strategy based on fixed embedding principle is determined and a multi-period SUE assignment model as well as the algorithm is given.

Based on the analysis of petrochemical process control, this article put forward a point that the essential of manpower intervention is superintendence control, whose main function is to optimize operation.