Elsa hates going shopping, 　　　 she went last night when her grandpa asked her to buy some medicine for him.

A．because

B．but

C．if

D．so

后牙牙槽嵴吸收较严重，为便于清洁，金一瓷桥的桥体与牙嵴的关系最好为（）

A.盖嵴式

B.单侧接触式

C.鞍基式

D.船底式

E.悬空式