A good textbook should guide teachers by comply-ing with and providing information about the funda-mental theories and principles of modern languageteaching approaches.This paper analyses the problemsexisting in the w...A good textbook should guide teachers by comply-ing with and providing information about the funda-mental theories and principles of modern languageteaching approaches.This paper analyses the problemsexisting in the widely used textbook for non-Englishmajors College English Focus Listening,and puts for-wards some suggestions for the improvement of thetextbook.展开更多
In this paper we study the decision problem of the center or focus for a class of planar polynomial fields which can be changed into Abel equation. Taking a Poincaré return map h(x) , we can calculate any orde...In this paper we study the decision problem of the center or focus for a class of planar polynomial fields which can be changed into Abel equation. Taking a Poincaré return map h(x) , we can calculate any order derivative of h(x) at x=0 and obtain the focus value of each order. The new method in this paper avoids the recurence operation and reduces the work in calculating the focus value.展开更多
文摘A good textbook should guide teachers by comply-ing with and providing information about the funda-mental theories and principles of modern languageteaching approaches.This paper analyses the problemsexisting in the widely used textbook for non-Englishmajors College English Focus Listening,and puts for-wards some suggestions for the improvement of thetextbook.
文摘In this paper we study the decision problem of the center or focus for a class of planar polynomial fields which can be changed into Abel equation. Taking a Poincaré return map h(x) , we can calculate any order derivative of h(x) at x=0 and obtain the focus value of each order. The new method in this paper avoids the recurence operation and reduces the work in calculating the focus value.
