1. 概念。
表示过去发生的动作对现在的影响和结果依然存在（已完成）。常与副词already（肯定）,yet（否定，疑问）,just,ever,never,once,twice,befoe等连用。
如： we h**e already known each other.
i h**e just washed my face.
he has been to this island before.
⑵也表示过去发生的动作或状态一直持续到现在，且有可能继续下去（未完成）。常与for（+时间段）,since（+时间点或过去时的句子）,so far等表示一段时间的状语连用。如：
如： we h**e lived there since 2000.
has been in beijing for over thirty years.
he has learned english since he was 6 years old.
注：这种用法中的动词用延续性动词。非延续性动词要用延续性动词代替。
常见非延续性动词与延续性动词的转换：buy—h**e borrow—keep come—be here le**e/go—be away begin/start—be on die—be dead join—be in
如：i h**e kept(borrow) the book for two weeks.
she has had(buy) this bike for a year.
the old man has been dead(die) since last year.
they h**e been away(le**e) for two hours.
2. 句型结构。
肯定句：主语 + h**e/has + 动词过去分词 + 其他。(主语是第三人称单数时用has，其他人称用h**e)。
如：i h**e done my homework since 6:00.
they h**e found the lost boy.
she has gone to beijing since she was 16 years old.
否定句：主语 + h**e/has + not + 动词过去分词 + 其他。
如： they h**e worked for 20 hours.→they h**en’t worded for 20 hours.
he has had his breakfast.→he hasn’t had his breakfast.
⑶一般疑问句： h**e/has + 主语 + 动词过去分词 + 其他？
如：she has been to beijing.→has she been to beijing?
yes,she has./no,she hasn’t.
they h**e already learned three english songs.→h**e they learned three english songs yet?
--yes,they h**e./no,they h**en’t.
⑷特殊疑问句：特殊疑问词 + 一般疑问句？
如： how many words has he learned yet?
how long hawe you lived here?
注：h**e/has been to 表示“去过某地”（已回来）.瞬间动词形式。
h**e/has gone to 表示“去某地了”（还未回来）人不在说话处，主语常用第三人称。
h**e/has been in 表示“已经。。。持续的）.持续性动词形式。
3.过去分词变化规则。
规则动词过去分词同过去式。
不规则动词需要记忆。
aaa型。1) cost—cost—cost 2) cut—cut—cut 3) hit—hit—hit
4) hurt—hurt—hurt 5) let—let—let 6) put—put—put
7) read—read—read 8) set—set—set 9) shut—shut—shut
②aab型。
1) beat—beat—beaten
aba型。1) become—became—become 2) come—came—come 3) run—ran—run
abb型。1) bring—brought—brought 2) buy—bought—bought 3) think—thought—thought
4) catch—caught—caught 5) teach—taught—taught 6) build—built—built
7) lend—lent—lent 8) send—sent—sent 9) spend—spent—spent
10) lose—lost—lost 11) smell—smelt—smelt 12) burn—burnt—burnt
13) feel—felt—felt 14) learn—learnt—learnt 15) hear—heard—heard
16) mean—meant—meant 17) keep—kept—kept 18) sleep—slept—slept
19) sweep—swept—swept 20) tell—told—told 21) stand—stood—stood
22) understand—understood—understood 23) say—said—said
24) pay—paid—paid 25) meet—met—met 26) le**e—left—left
27) hold—held—held 28) dig—dug—dug 29) find—found—found
30) get—got—got31) hang—hung—hung 32) h**e—had—had
33) make—made—made 34) shine—shone—shone 35) sit—sat—sat
36) win—won—won
abc型。1) blow—blew—blown 2) draw—drew—drawn 3) fly—flew—flown
4) grow—grew—grown 5) throw—threw—thrown 6) know—knew—known
7) choose—chose—chosen 8) eat—ate—eaten 9) fall—fell—fallen
10) ride—rode—ridden 11) rise—rose—risen 12) hide—hid—hidden
13) see—saw—seen 14) shake—shook—shaken 15) take—took—taken
16) mistake—mistook—mistaken 17) wake—woke—waken
18) write—wrote—written 19) be—was/were—been 20) do—did—done
21) break—broke—broken 22) forget—forgot—forgotten 23) give—g**e—given
24) freeze—froze—frozen 25) begin—began—begun 26) ring—rang—rung
27) drink—drank—drunk 28) go—went—gone 29) lie—lay—lain
30) sing—sang—sung 31) swim—swam—swum 32) wear—wore—worn
33) show—showed—shown 34) sink—sank—sunk
练习：a．用所给词的适当形式填空。
1. we __already___clean) the classroom .
2. h**e you___get) a bike? yes, i___
3. h**e you___write) a letter to tom? n o, i___
4. shenot see) the film before.
5. li lei___just___eat)fish and chips.
6. inot do) my homework yet.
7. tom and jimbe) to the great wall before.
8. my motherbuy) a new car for a week.
9. a: has she been to beijingb: yes, she __
a: when __she __go) there? b: last month.
10. _you___finish)your work? no, not yet.
b.用for 和since填空。
1. we h**e learned five hundred words __the beginning of this term.
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