单词学习：tier 名词/动词
tier
/tɪr/
n. 层；排；等级；行；vt. 使层叠；vi. 成递升排列
The students were seated in three tiers, and Gu Laoshi stood at the front of the highest tier to give her lecture.
学生们分三层就座，顾老师站在最高层的前面讲课。
单词卡片
卡片已就绪
