—Isn't it a surprise that I happened to meet Francis Mafhews at the Christmas party last week?

—If my memory serves me correctly, you ____ each other for exactly two years. [ ]

A. hadn't seen

B. haven't seen

C. didn't see

D. don't see.

当液压系统种A系统低压时（）

A.A系统PCU失去压力，有一侧副翼无法动作

B.A系统PCU由B系统提供压力，副翼可以正常操作

C.A系统PCU由备用液压系统提供压力，副翼可以正常操作

D.A系统PCU失去压力，由B系统副翼PCU操纵副翼