同时在融资买入以及融券卖出的方程中，他们之间是互为外生变量的。
Through the test financing to buy and sell securities are exogenous variables with each other .
该模型建立在允许买空和卖空的情形下，即可以融资买入或者融券卖出。
This model is allowing short buying and short selling the securities , which means the margin trading .
融券卖出