The rim is flat and there is a rather deep well, or cavetto.

边缘是平坦的，有当深的底部，或称为圆底。

This paper introduces a simple semimicro-distillation apparatus,In this apparstus,a three-necked flask is used as steam generator.

文介绍种用三颈圆底为蒸汽发生器的半微量水汽蒸馏装置。