Mrs White. bought a _____ wallet for her husband.

A．black leather small

B．small leather black

C．black small leather

D．small black leather

下列哪种物质可使食管下端括约肌（LES）收缩（）

A.盐酸

B.内因子

C.碱性粘液

D.促胃液素

E.胃蛋白酶