The beginning of second crack is an indicator that the coffee is nearly done and you should be ready to end the roast very soon.
二爆的开始是咖啡豆接近烘焙好的指标，并且需要尽快关火结束。
2
It has been proved that shrinkage can't be used as the indicator of crack resistance of concrete and the evaluation experiments should be carried out under restrained conditions.