英语常用动词变形为啥不规则

这涉及到英语语言的发展历史.英语是从凯尔特语的基础上发展起来的,过程中经常借用其他语言中现成的词汇.你说的都基本是凯尔特语的词汇,在古英语中,很多动词的变形都与现在不同.
其实不用深究,不然的话你就得学习一下两门英语专业的本科高年级专业课,语言学和词汇学.
给你常用的动词变形吧
1.A---A---A型（现在式、过去式和过去分词同形）
动词原形（现在式）过去式 过去分词
cost cost cost 花费
cut cut cut 割,切
hit hit hit 打
let let let 让
put put put 放下
read read read 读
hurt hurt hurt 伤
2.A---A---B型（现在式和过去式同形）
beat beat beaten 打
3.A---B---A型（现在式和过去分词同形）
come came come 来
become became become 变
run ran run 跑
overcome overcame overcome征服,打败,克服
4.A ---B ---B型
（1）在动词原形后加一个辅音字母d或t构成过去式或过去分词.
burn burnt burnt 燃烧
learn learned/learnt learned/learnt 学习
mean meant meant 意思
hear heard heard 听见
（2）把动词原形的最后一个辅音字母“d”改为“t” 构成过去式或过去分词.
build built built 建筑
lend lent lent 借给
lose lost lost 失去
send sent sent 送
spend spent spent 花费
（3)
pay paid paid 付
lay laid laid 下蛋
say said said 说
(4)
bring brought brought 带来
buy bought bought 买
fight fought fought 战斗
think thought thought 想
(5)
sleep slept slept 睡
feel felt felt 觉得
keep kept kept 保持
sweep swept swept 扫
(6)
stand stood stood 站
understand understood understood 明白
(7)
win won won 得胜
(8)
catch caught caught 抓住
teach taught taught 教
(9)
find found found 发现
get got got 得到
hold held held 盛,握
leave left left 离开
make made made 制造
meet met met 遇见
shoot shot shot 射击
dig dug dug 挖
(10)
shsmell smelt/smelled smelt/smelled 嗅,闻
shine shone/shined shone/shined 发光
（11)
tell told told 告诉
sell sold sold 卖
(12)
sit sat sat 坐
have had had 有
5.A---B---C型（现在式、过去式和过去分词都不相同）
（1）在动词原形后加-n或-en构成过去分词.
eat ate eaten 吃
fall fell fallen 落下
steal stole stolen 偷
give gave given 给
freeze froze frozen 冻结
take took taken 拿
see saw seen 看见
write wrote written 写
ride rode ridden 骑
drive drove driven 驾驶
throw threw thrown 抛,扔
blow blew blown 吹
grow grew grown 生长
know knew known 知道
fly flew flown 飞
draw drew drawn 拉,绘画
show showed shown 展示
（2）过去式加-n或-en构成过去分词.
speak spoke spoken 说话
break broke broken 破碎,折断
wake waked/ woke waked/ waken 醒
choose chose chosen 选择
forget forgot forgotten 忘记
（3）变单词在重读音节中的元音字母“i”分别为“a”（过去式）和“u”（过去分词）.
begin began begun 开始
ring rang rung 按铃
sing sang sung 唱
sink sank sunk 沉
swim swam swum 游泳
drink drank drunk 饮
（4）其他不规则动词的变化.
be(am,is) was/ were been 是
be(are) were been 是
do did done 做
go went gone 去
lie lay lain 躺
wear wore worn 穿