crack /kræk/ I. n. ［c］ the crack of thunder 雷声 ‖II. vi.& vt. 1. （使）裂开(一条缝)，裂化: Don’t pour hot water into the glass, or it will crack. 不要把滚开的水倒进玻璃杯，否则要裂的。Crack me a nut, please. 请给我砸一个核桃。A cracked bell never sounds well. 有缝的钟永远没有好声音。 2.发出爆裂声: The tree cracked loudly and fell. 树劈啪作响接着就倒下来了。3. 用于短语动词crack down on严加管理：The parents are demanding that teachers should crack down on bad behaviour in the classroom. 家长们要求老师对教室里的不良行为要严加管理。crack up令人突然发笑；突然撞上：They cracked up when they saw me in that hat. 他们看到我戴着那个帽子就笑起来。Zach cracked up a car while blind drunk.扎克醉得很厉害，一头碰了一辆汽车。