关于食管下括约肌的叙述，下列哪项是错误的（）。

A.该部位平滑肌增厚

B.正常人休息时食管下括约肌压力为10～30mmHg

C.食管下括约肌长约2～4cm

D.促胃液素可刺激其收缩

E.可防止胃内容物逆流入食管

I study in High School Affiliated to Southwest University. There are __________ students in our school. Nine ______________ of them are girls.

A．thousands of; hundred

B．thousand of; hundreds

C．thousand of; hundred

D．thousands of; hundreds