一發〔-发〕 jat¹ faat³ {yī fā}

classifier for bullets

一髮千鈞〔-发-钧〕 jat¹ faat³ cin¹ gwan¹ {yī fà qiān jūn}

thousand unit of weight is hang on to one single hair, which describes the situation is very dangerous

一發不可收拾〔-发----〕 jat¹ faat³ bat¹ ho² sau¹ sap⁶ {yī fā bù kě shōu shi}

1. things that have happened can hardly be controlled
2. to get out of hand