adj.三層的；三重的；三股的
n.三重；三股；三層夾板
Their wedding cake had three tiers. 他們的結(jié)婚蛋糕是三層的。
This is a rope of three strands. 這是一條三股的繩子。
Biodegradation has at least three definitions. 生物降解至少有三重含義。
