1. 减少(生产成本)：lengthen 延长 | lessen 减少(生产成本) | level 水平
2. lessen的解释
2. 下降：上升:increase, rise ,ascend ,core, surge,go up, climb ,mount ,level... | 下降: decrease, fall, drop ,descend ,decline ,reduce ,lessen ,level down | 波动:fluctuate ,fluctuation ,rise and falls ,up and d...
3. 减少：lesson#功课 | lessen#减少 | return#回来
4. 使小;变小;减少：lesser更少的(地更小的(地) | lessen使小;变小;减少 | lesson教训, 训诫, 惩戒