Because of the low strength,an optimal tension control system based on the master-slave structure is developed in order to prevent the breakage of the micro wire electrode.

To be clear about the two kinds of relationships,students should first draw a treediagram of subordinate construction,and then try to cover different possibilities of sentence pattern transformation.

Based on teaching practices, the paper points out that subordinate structure is an acquiring difficulty for Chinese students English learning and one of the most important factors restricting students translating and writing standards.