While stressing that the native language transfer inevitably exerts definite influences on English study,the paper is to give a more detailed analysis to the positive and negative effects of the native language transfer in the course of foreign language study.

Suppose that each driver perceives his/her travel disutility as a weighting of travel time and travel cost and makes route choice in a logit-based stochastic equilibrium manner but the drivers equipped with advanced traveler information system (ATIS) have lower perception variations than the unequipped.

In a general principal agent analysis model,it should be considered the impact of uncertain state on the agent s effort cost.

This paper points out that the principal and agent may have different prior probability to the uncertain state of world, and the influence of state to the agent s effort cost should be considered inthe principal-agent analysis model.