1、
Each ball bearing has three main parts: two grooved , ringlike races and a number of balls.
球轴承有三个主要零件, 即 两个带有沟槽的套圈和许多球.
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2、
Surrounding the end of the stomach is a ringlike muscle called pyloric valve.
围绕在胃末端的是一片环状肌肉叫做幽门瓣.
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