2.Observational studyaims at the approach to a dynamic system whose equation is undeterminable.
该方程组的解有限时段上的采样值与给定序列重合。
3.Pectose exists in the fleshy pulp of unripe fruit;during the process of ripening it changes to pectin;by cooking, pectin is changed to pectosic acid, and by longer cooking to pectic acid.