试述通气／血流比值（V/Q）。
既能敛肺降火又能敛汗止血的药物是（） ["五倍子","乌梅","莲子","五味子","诃子"]
莲子、芡实二者的共同功效是（） ["益肾固精，补脾止泻，止带","益气生津，补脾止泻，止带","涩肠止泻，益肾固精，安神","敛肺止咳，涩肠止泻，安神","收敛固涩，益气生津，止带"]
既可涩肠止泻又可温中行气的药物是（） ["五味子","肉豆蔻","五倍子","赤石脂","诃子"]
对久泻久痢，涩肠止泻的圣药是（） ["五味子","乌梅","五倍子","罂粟壳","诃子"]
试述气体分布测定的临床意义。
