铸造缺陷 、 杂质元素偏聚和夹杂物的存在是形成早期裂纹源的原因.用英语怎么说？

铸造缺陷 、 杂质元素偏聚和夹杂物的存在是形成早期裂纹源的原因.

Reasons of forming first cracks were foundry lacuna, impurity gathering , lard exiting.

reasons

n. 理由( reason的名词复数 )，原因，理性，理智；v. 推理，思考( reason的第三人称单数 )，争辩；

例句
Several people buttonholed television reporters to explain to them their reasons for not voting.
几个人拉住电视台记者非要向他们解释自己不投票的理由。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

forming

n. 形成，组成，构成，编成；v. 形成，构成，产生( form的现在分词 )，是，（使）成形，结成（友谊）；

例句
Everybody knows they haven't got a hope in hell of forming a government anyway.
众人皆知他们根本就无力组建政府。

first

n. 第一，最初，头等，一号，，[乐]高音部；adv. 最早，最初，首次，宁愿，优先；adj. 第一流的，最初的，最早的，基本的，概要的，高音的；num. 第一；

例句
He abbreviated his first name to Alec.
他将自己的名字缩写为亚历克。

cracks

v. 打开( crack的第三人称单数 )，（使…）开裂，说（笑话），开瓶；

例句
The cracks are showing in the walls and a lick of paint would not come amiss.
墙面开始出现裂缝了，刷一点油漆就能补好。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

foundry

n. 铸造厂；

例句
The moulds for the foundry are made in the tool-room area.
铸造车间的模具是在工具间生产的。

lacuna

n. 空白，空隙，腔隙，缺陷；

例句
There was so much very deep lacuna in his crude big hands.
粗糙的大手上一道道很深的裂口.

impurity

n. 污点，污染，掺杂，不纯，不道德，罪恶，混杂物，粗劣品；

例句
...a sphere made of diamond without impurity or flaw.
用钻石制成的完美无瑕的圆球

gathering

n. 聚集，集会，采集，积累；v. （使）聚集( gather的现在分词)，集合，推断，了解；

例句
The script has been gathering editorial accretions for years.
多年来该剧本一直在修改。

lard

n. 猪油；vt. 润色，涂猪油于，将肥猪肉片嵌于（牛肉或禽肉）中，（在讲话或文章中）夹杂大量（某类词语）；

例句
Put water, butter and lard into a saucepan and bring slowly to the boil.
把水、黄油和猪油倒入平底锅，然后慢火煮沸。

exiting

v. 离开，退场( exit的现在分词 )；

例句
Upon exiting the break room, put on work and boots and coveralls, if needed.
走出休息室后, 有必要的话应该穿上工作靴和工作服.