单心室的病理生理改变，不会出现的是（）。

A.心室扩张

B.心力衰竭

C.肺动脉高压

D.心室壁增厚

E.差异型发绀

To prevent the buyer from opening the L/C late，the exporter should stipulate at the same time in the contract：“The relevant L/C must reach the seller not later than one month before the date of the shipment”．( )