Moreover, a group of equations for determining the intrinsic specific properties of the thermal efficiency of a solar cooker is also provided and a thermal efficiency chart is designed.

The relation of distribution coefficient ( C u ) and deviation coefficient ( C v ) in normal distribution are proved and the advantages of using pattern efficiency ( E p ) in practice are analysed, which have certain effect to practice.

On the basis of Long-term AutoCAD teaching practice and analysis of problems drawn by students in AuotCAD, the paper researchs into following principle; clever orders; mastering skill; express tools; expanding function five subjects in AutoCAD drawing, in order to grasp the way and method of raiseing drawing efficiency to enhance students s drawing ability.