－般保证未约定保证期限间地，保证期限间为主债务履行期限届满之日起（）。（担保法第２5条）
A.3个月
B.6个月
C.180天
D.90天
参考答案：B
I think you probably know China has adopted a flexible policy( )her foreign trade.
A. on B. withC. in D. under
