Point to two bricks to after clipping, be bumped each other with the hand, ringing canorous is sound eligible product, sound is grave of frowsty chaotic have immanent quality drawback necessarily.

• 将两块砖用手指夹住后相互撞击，声音清脆响亮的为合格产品，声音低沉闷浊的必然有内在的质量缺陷。