Then,an exposure index model representing the degree of traveler\'s exposure to vehicle emissions was established,and the effects that the vehicle emissions impose on the travel choices were quantitatively evaluated by the new definition of vehicle emission extra time.

Sunk costs in renovation and expansion projects were introduced, and the approaching ways were discussed with incremental analysis method It was considered that though sunk cost had its essence of sinking, it can bring economic profit to enterprises should it be utilized correctly.