break : 常用词，含义广泛，多指猛然用力将坚硬物打破或损坏。
The dish fell to the floor and broke.碟子掉到地上摔碎了。Charles is always breaking things.查尔斯老是打碎东西。She fell and broke her arm (= broke the bone in her arm).她摔断了胳膊。I dropped the vase and it broke into pieces.我把花瓶掉在地上摔碎了。crack : 多指因长期使用或经受压力，物体表现呈现裂纹、裂口或破裂、裂开，但一般没成碎片。A stone hit the window and cracked the glass.石块击中窗户，打裂了玻璃。I cracked my tooth as I fell.我摔倒时把牙齿磕了一道裂缝。The walls cracked and the roof collapsed in the earthquake.地震中墙壁开裂，屋顶坍塌。
