In heavy smokers,the MET elongated to 127% of the predicted value and in the convex type F V curve, it elongated to 120% of the predicted value;

• MET在重度吸烟组延长到预计值的127%25 ，在凸型F－V 曲线延长到120%25 ，均与相应组别的·V50 、·V25 下降一致。