特殊用法open tier1.开放层(指裸子植物原胚)pallet tier1.货垫垛prosuspensor tier1.原胚柄层rosette tier1.莲座层suspensor tier1.胚柄层three tiers of berths1.三层卧铺upper tier1.上层(指原胚)tier of bags1.堆垛的装袋产品tier of beams1.横梁层