— Is that the country clinic you often refer to?

— Right，just the one_________you know my father used to work for 10 years

A．that

B．which

C．where

D．as

牙周炎与边缘性龈炎的区别点在于牙周炎表现为

A．龈缘有炎症

B．龈 * * 有炎症

C．形成真性牙周袋

D．牙不松动

E．无牙槽骨吸收