月经后期与月经过少均具备的发病机制是（）

A.血为寒凝，冲任阻滞

B.瘀血内停，冲任阻滞

C.痰湿内盛，滞于冲任

D.血为气滞，冲任不畅

E.阳虚内寒，胞脉失养

There ______ lots of old buildings here in the past.      [ ]

A. was              

B. used to have      

C. used to be