There are two common types in page replacement algorithm: stack and non-stack strategies. When a real page number increase only stack algorithm can increase the hit rate monotonously. In the following replacement algorithm, which one belongs to non-stack strategy( ).

A．FIFO

B．LRU

C．PFF

D．OPT

双室模型静脉注射血药浓度与时间的关系是（）

A.

B.

C.

D.

E.