不规则动词的过去式和过去分词变化规则表1：
1、A—A—A型，即原形、过去式和过去分词三者都相同。
cost—cost—cost cut—cut—cut hit—hit—hit hurt—hurt—hurt let—let—let
put—put—put read—read—read
2、A—B—B型，即过去式、过去分词相同。
1) 过去式和过去分词都含有-ought。
bring—brought—brought buy—bought—bought think—thought—thought
fight-fought-fought
2) 词尾有-ild，-end时，只需把d变为t。
build—built—built lend—lent— lent send—sent—sent spend—spent— spent
3) 过去式、过去分词都含有-aught。
catch—caught—caught teach—taught—taught
4) 把-eep变为-ept。
keep—kept—kept sleep—slept—slept sweep— swept—swept
5) 把-ell变为-old。
tell—told—told sell—sold—sold
6) 过去式、过去分词都含有-elt或-ilt。
smell—smelt—smelt spell—spelt—spelt feel—felt—felt
7) 过去式、过去分词都在原形词尾加t。
learn—learnt—learnt mean—meant—meant
8) 过去式、过去分词词尾去y变-id。
say—said—said pay—paid—paid lay—laid—laid hear—heard—heard
9) 改变元音字母。
meet—met—met get—got—got sit—sat—sat find—found—found hold—held—held shine—shone—shone win—won—won hang—hung—hung lose—lost—lost
10) 改变辅音字母。
make—made—made
11) 改变元、辅音字母。
leave—left—left stand—stood—stood have(has)—had—had understand—understood—understood
3、A—B—C型，即原形、过去式、过去分词都不相同。
1) 原形、过去式和过去分词都不相同。
be—was—been do—did—done fly—flew—flown go—went—gone lie—lay—lain show—showed—shown wear—wore—worn
2) 词尾为-ow，-aw时，过去式将其变为-ew，过去分词在其原形后加n。
blow—blew—blown draw—drew—drawn grow— grew—grown know—knew—known throw—threw—thrown（show除外）
3) 词尾为“i＋辅（1个）＋e”，过去式将i变为o，过去分词多在原形后加n，若那个辅音字母为d或t，须双写d或t后加n。（give，hide除外）
drive—drove—driven write—wrote—written ride— rode—ridden rise—rose—risen arise—arose—arisen
4) 过去分词在过去式后加（e）n。
break—broke—broken choose—chose—chosen freeze—froze—frozen speak—spoke—spoken wake—woke—woken
5) 过去分词由过去式加-ten构成。
forget—forgot—forgotten
6) 过去分词由原形加（e）n构成。
be—was（were）—been eat—ate—eaten fall—fell—fallen give—gave—given see—saw—seen hide—hid—hidden（hid）
7) 词尾为-ake时，过去式将其变为-ook，过去分词在原形词后加-n。
take—took—taken mistake—mistook—mistaken
8) i—a—u变化。
begin—began—begun drink—drank—drunk sing— sang—sung ring—rang—rung swim—swam—swum sink— sank—sunk
4、A—B—A型，即过去分词和原形相同。
come—came—come become—became—become run—ran—run
5、情态动词型，只有原形和过去式，没有过去分词。
can—could may—might will—would shall—should
不规则动词的过去分词变化规则表2：
(1) AAA型（动词原形、过去式、过去分词同形）
cost cost cost
cut cut cut
hit hit hit
hurt hurt hurt
let let let
put put put
read read read
(2) AAB型（动词原形与过去式同形）
beat beat beaten
(3) ABA型（动词原形与过去分词同形）
become became become
come came come
run ran run
