According to the current international trade theory,B/L is negotiable,and straight B/L is one kind of B/L.

With a history of more than 200 years, the division of labor theory in international trade has gone through three stages: the classical period, the neo-classical period and the new trade theory period, each having distinct features in the development of international trade.

International trade theory originated from the economic ideas of mercantilism.

The development of phenomenography can be divided into five different phases: (1) investigating students differences in learning; (2) studying variation in people s ways of experiencing; (3) developing a framework to characterise people s ways of experiencing; (4) applying the variation theory to describe and analyse classroom teaching; and (5) finally designin.

This study aims at making use of the variation theory to examine the relationship between learner\'s autonomy and teacher\'s scaffolding.

As an imitation of the Orderly Sequence of the Hexagrams of Zhouyi by WANG Anshi, Yi xiang lun jie (Commentaries on and Interpretations of the Yi images) is a kind of new Orderly Sequence of the Hexagrams.