sag
/sæg; sæɡ/ v
(-gg-) [I]
1 sink or curve down in the middle under weight or pressure （因负重或受压）向下凹或中间下陷
a sagging roof 下陷的屋顶
The tent began to sag as the canvas became wet. 帐篷因帆布湿了中间有些下坠.
2 hang loosely or unevenly 松弛或不整齐地悬著
old torn curtains sagging at one end 垂在一端的破旧窗帘
Your skin starts to sag as you get older. 人一老皮肤就松弛了. sag, n [U, sing]
extent to which sth sags; sagging 下陷或松弛的程度; 下陷或松弛
too much sag in the mattress 床垫过於松弛
a sag in the seat of the chair 椅子座位部分的凹陷.