问题如下：
All else equal, which of the following was not a factor to increase the government deficit?
选项：
A.an increase in the excess of private saving over private investment.
B.an increase in net export.
C.a increase in trade deficit
解释：
B is correct.
The fiscal balance equation is given as: (G-T)=(S-I)-(X-M), An increase in government deficit (G-T) is a combination of increase in private saving over private investing (S-I) and a decrease of trade deficit or net export (X-M).
考点：Relationship between Income Approch and Expenditure Approach
解析：
财政平衡方程为:(G-T)=(S-I)-(X-M)，政府赤字(G-T)的增加的同时，私人储蓄增加超过私人投资(S-I)，或者贸易赤字或净出口(X-M)减少，所以AC选项不入选，B选项入选。
当G-T增大的时候, 不就意味着S-I增大或X-M减小么
那答案里面,应该是净出口(净出口一般为正数)减小, 而贸易赤字增大.
那正确答案不应该是选C才对么?
