crash
crash模仿的是两个物体猛烈碰撞到一起时发出的“咔嚓”声。自然界中能发出类似声响的现象太多了，所以很多cr开头的单词都有紧贴、碰撞、挤压、破裂的含义

(AmE also wreck) an accident in which a vehicle hits sth, for example another vehicle, usually causing damage and often injuring or killing the passengers:
a sudden loud noise made, for example, by sth falling or breaking
a sudden serious fall in the price or value of sth; the occasion when a business, etc. fails
a sudden failure of a machine or system, especially of a computer or computer system:
Of or characterized by an intensive effort to produce or accomplish
n. 碰撞；崩溃；坠落
vt. 坠落；破碎；撞碎
vi. 碰撞；坠毁；闯；突然倒台
adj. 速成的(加倍努力产生或完成的)

例句：
The motorcycle crashed into the fence.
摩托车猛地撞在围栏上。
A lot of passengers were killed in the train crash.
许多旅客在火车车祸中丧生了。

crack
to break without dividing into separate parts; to break sth in this way
to break open or into pieces; to break sth in this way:
~ sth/sb (on / against sth) to hit sth/sb with a short hard blow
to make a sharp sound; to make sth do this:
Excelling in skill or achievement; first-rate
vt. 使破裂；打开；变声
vi. 破裂；爆裂
n. 裂缝；声变；噼啪声
adj.一流的，顶尖的， 最好的（短语 Be a crack shot 百发百中 ）

常用词组:
crack the whip
To behave in a domineering manner; demand hard work and efficiency from those under one's control.
盛气凌人地：以盛气凌人的方式表现；要求其下属努力并有效地干活
crack down
To act more forcefully to regulate, repress, or restrain:
严厉取缔：采取严厉措施来规定、抑制或约束：

例句：
The glass cracked when I poured icy water into it.
当我把冰水倒进杯子时,杯子裂开了。
He is a crack baseball player.
他是个呱呱叫的棒球运动员。

cramp
A sudden, involuntary, spasmodic muscular contraction causing severe pain, often occurring in the leg or shoulder as the result of strain or chill.
A temporary partial paralysis of habitually or excessively used muscles.
cramps Spasmodic contractions of the uterus, such as those occurring during menstruation or labor, usually causing pain in the abdomen that may radiate to the lower back and thighs.
To affect with or as if with a cramp.
To restrict or prevent from free action or expression.
n. 痉挛，绞痛；[五金] 铁夹钳
vt. 束缚，限制；使…抽筋；以铁箍扣紧
adj. 狭窄的；受限制的

例句：
Her education was cramped by her lack of money.
她因缺钱而无法深造。
The swimmer was seized with a cramp and had to be helped out of the water.
那个在游泳的人突然抽起筋来,让别人帮着上了岸。

crump
To crush or crunch with the teeth.
To strike heavily with a crunching sound.
To make a crunching sound, especially in walking over snow.
A crunching sound. The sound of an exploding shell.
A heavy blow.
n. 嘎吱声;爆炸声;重击
vi. 发嘎吱嘎吱声；猛烈爆炸
vt. 嘎吱作响地嚼

crumb
A very small piece broken from a baked item, such as a cookie, cake, or bread.
A small fragment, scrap, or portion: eraser crumbs; not a crumb of kindness for you.
The soft inner portion of bread
To break into very small pieces; crumble.
To cover or prepare with very small pieces of bread.
To brush (a table or cloth) clear of small scraps or fragments of food.
n. 面包屑，碎屑；少许
vt. 弄碎；捏碎

例句：
He gave me a few crumbs of information about the writer.
他为我提供了有关这位作家的一些情况。
She crumbed the bread before feeding it to the birds.
她把面包弄碎,然后喂给鸟吃。