A、增加 B、減少 C、不變 D、增加或減少
A、(TH+TL)/TH B、TH/(TH-TL) C、TL/(TH-TL) D、(TL-TH)/TH
A、(TH-TL)/TH B、TH/(TH-TL) C、TL/(TH-TL) D、(TL-TH)/TH