小紅家春天粉刷房間，雇用了5個工人，幹了10天完成；用了某種塗料150昇，費用為4800元，粉刷的面積是150m2.最後結算工錢時，有以下幾種方案：方案一：按工算，每個工30元；（1個工人幹1天是一個工）；方案二：按塗料費用算，塗料費用的30%作為工錢；方案三：按粉刷面積算，每平方米付工錢12元.請你幫小紅家出主意，選擇______付錢最合算（最省）.

小紅家春天粉刷房間，雇用了5個工人，幹了10天完成；用了某種塗料150昇，費用為4800元，粉刷的面積是150m2.最後結算工錢時，有以下幾種方案：方案一：按工算，每個工30元；（1個工人幹1天是一個工）；方案二：按塗料費用算，塗料費用的30%作為工錢；方案三：按粉刷面積算，每平方米付工錢12元.請你幫小紅家出主意，選擇______付錢最合算（最省）.

第一種方案的薪水=30×10×5=1500（元）；第二種方案的薪水=4800×30%=1440（元）；第三種方案的薪水=150×12=1800（元）.答：選擇方案二付錢最合算（最省）.

一種蔬菜加工後出售，單價可提高30%，但重量要降低15%，現有未加工的這種蔬菜2000千克，加工後共賣了2652元，則加工後比不加工多賣______元.

設加工前每千克賣x元，由題意得：（1+30%）x×（1-15%）×2000=2652，解得x=1.2.1.2×2000=2400（元），2652-2400=252（元）.故答案為：252.

在三角形ABC中，若已知三邊為連續正偶數，最大角為鈍角.（1）求最大角的余弦值，（2）求以此最大角為內角

最大角為鈍角，可知倆較短邊平方和小於最大邊（余弦定理），解不等式有兩組2,4,6；4,6,8，前一組不滿足兩邊之和大於第三邊.故，三角形邊長為4,6,8

動詞過去式和過去分詞不規則變化的規律
除了形式ABC外還要單詞變化的規律
11月17日9:20前有效

規則動詞的過去式變化如下：
一般情况下，動詞詞尾加-ed，如：
worked played wanted acted
以不發音的-e結尾動詞，動詞詞尾加-d，如：lived moved decided declined hoped judged raised wiped
以輔音字母+ y結尾的動詞，把-y變為-i再加-ed，如：
studied tried copied justified cried carried embodied emptied以一個輔音字母結尾的重讀閉音節動詞，雙寫詞尾輔音字母，再加-ed，如：stopped begged fretted dragged dropped planned dotted dripped注：不規則動詞的過去式變化規律性不强，須多加記憶.
go - went make - made get - got buy - bought come - came fly-flew
動詞過去式，過去分詞不規則變化
AB型
can could shall should
will would may might
AAA型
cost cost cost
cut cut cut
hit hit hit
hurt hurt hurt
let let let
must must must
put put put
set set set
shut shut shut
read read read
AAB型
beat beat beaten
ABA型
become became become
come came come
run ran run
ABB型
bring brought brought
buy bought bought
think thought thought
catch caught caught
teach taught taught
build built built
lend lent lent
send sent sent
spend spent spent
dig dug dug
hang hung hung
feel felt felt
keep kept kept
sleep slept slept
sweep swept swept
leave left left
smell smelt smelt
spill spilt spilt
lay laid laid
pay paid paid
say said said
sell sold sold
tell told told
sit sat sat
spit spat spat
stand stood stood
understand understood understood
learn learnt learnt
mean meant meant
spoil spoilt spoilt
shine shone shone
win won won
have had had
make made made
hear heard heard
find found found
hold held held
ABC型
begin began begun
drink drank drunk
ring rang rung
sing sang sung
sink sank sunk
swim swam swum
blow blew blown
fly flew flown
grow grew grown
know knew known
throw threw thrown
draw drew drawn
show showed shown
break broke broken
choose chose chosen
forget forgot forgotten
freeze froze frozen
speak spoke spoken
wake woke woken
drive drove driven
eat ate eaten
fall fell fallen
give gave given
hide hid hidden
ride rode ridden
rise rose risen
take took taken
mistake mistook mistaken
write wrote written
am，is was been
are were been
do did done
go went gone
lie lay lain
see saw seen
wear wore worn
易錯型
show showed shown
draw drew drawn
fall fell fallen
feel felt felt
hold held held
help helped helped
think thought thought
thank thanked thanked
take took taken
talk talked talked
get got got
forget forgot forgotten
meet met met
mean meant meant
hit hit hit
hide hid hidden
ring rang rung
bring brought brought
eat ate eaten
beat beat beaten
lie lay lain
lay laid laid
find found found
found founded founded
buy bought bought
bring brought brought
learn learnt learnt
hear heard heard
回答者：leosongyou -進士出身九級3-31 22:03
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5動詞過去式和過去分詞的變化規則
動詞過去式和過去分詞有規則變化和不規則變化兩種.
1）規則變化
情况例詞讀音與說明
動詞原形過去式過去分詞
一般在動詞原形後加-ed look
call
open
need looked
called
opened
needed looked [lukt]
called [kC:ld]
opened [5EupEnd]
needed [ni:did]①-ed在清輔音音素後
發音為〔t〕，在濁輔音後發音為〔d〕，在母音後發音也為[d]
②-ed在〔t]、〔d〕
後發音為[id]
③但fix的過去式和過去
分詞x不雙寫，為fixed.
以-e結尾的動詞加-d move
phone
hope
agree moved
phoned
hoped
agreed moved [mu:vd]
phoned [fEund]
hoped [hEupt]
agreed [E5^ri:d]
以輔音字母加y結尾的動詞，變y為i，
再加-ed study
carry
try studied
studied
carried studied [5stQdid]
carried [5kArid]
tried [traid]
以原音字母加y結尾的詞，直接加-ed play
enjoy
stay played
enjoyed
stayed played [pleid]
enjoyed [in5dVCid]
stayed [steid]
末尾只有一個輔音字母的重讀閉音節詞，雙寫該輔音字母，再加-ed stop
plan
fit stopped
planned
fitted stopped [stCpt]
planned [plAnd]
fitted [5fitid]
以-r音節結尾的詞，雙寫r字母，
再加-ed prefer
refer preferred
referred preferred [prI`f:d]
referred [ri5fE:]
2）不規則變化
英語中有些動詞的過去式和過去分詞形式變化不規則，可分為五種情况.
1.動詞原形、過去式和過去分詞完全同形.
例：
原形過去式過去分詞
cut（切）
hit（打）
cast（扔）
hurt（傷害）
put（放）
let（讓）
shut（關）
cost（花費）
set（放）
rid（清除）cut
hit
cast
hurt
put
let
shut
cost
set
rid cut
hit
cast
hurt
put
let
shut
cost
set
rid
2.過去式與過去分詞完全同形.
例：
原形過去式過去分詞
find（找到）
pay（支付）
leave（離開）
lend（借出）
meet（遇見）
keep（保持）
lose（遺失）
teach（教）
sit（坐）
lead（引導）
win（贏）除）found
paid
left
lent
met
kept
lost
taught
sat
led
won found
paid
left
lent
met
kept
lost
taught
sat
led
won
3.動詞原形與過去分詞同形
例：
原形過去式過去分詞
come（來）
run（跑）
become（成為）came
ran
became come
run
become
4.動詞原形、過去式、過去分詞形式完全不同.
例：
原形過去式過去分詞
give（給）
fly（飛）
drink（喝）
see（看見）
go（去）
know（知道）
wear（穿）
speak（說）gave
flew
drank
saw
went
knew
wore
spoke given
flown
drunk
seen
gone
known
worn
spoken
5.過去式和過去分詞有兩種形式
例：
原形過去式過去分詞
burn（燃燒）burned
burnt burned
burnt
learn（學習）learned
learnt learned
learnt
smell（聞）smelled
smelt smelled
smelt
spell（拼寫）spelled
spelt spelled
spelt
shine（照射）shined
shone shined
shone
leap（跳）leaped
leapt leaped
leapt
提示
a. beat的過去式與原形同形：
比：beat（打擊）beat（過去式）beaten（過去分詞）
b. lie有規則變化和不規則變化兩種，含義不同
比：lie lied，lied（說謊）
lay，lain（躺，位於）
c. hang有規則變化和不規則變化兩種，含義不同
比：hang hanged，hanged（處絞刑）
hung，hung（掛，吊）
d. welcome（歡迎）一詞是規則動詞，不可誤用為不規則動詞
比：welcome welcomed，welcomed（正）
welcome，welcome（誤）
e.不要將不規則動詞誤用為規則動詞
比：hit（打）hit，hit（正）
hitted，hitted（誤）
6現在分詞的變化規則
規則動詞原形現在分詞及發音
一般在動詞原形詞尾加-ing，-ing發音為[iN] go
push
play
carry going [5^EuiN]
pushing [5puFiN]
playing [pleiiN]
carrying [5kAriiN]
以不發音的e結尾的動詞，先去掉e，再加-ing take
write
leave taking [5teikiN]
writing [5raitiN]
leaving [5li:viN]
重讀閉音節結尾的動詞，如果詞尾只有一個輔音字母，要將該輔音字母雙寫，再加-ing cut
stop
fit
begin
forget cutting [5kQtiN]
stopping [5stCpiN]
fitting [5fitiN]
beginning [bi5^iniN]forgetting [fE5^etiN]
以ie結尾的動詞，要把ie改為y，再加-ing lie
die
tie lying [5laiiN]
dying [5daiiN]
tying [5taiiN]
後面是r的，加了ed是否要讀成類似“gather的”，直接加讀音d，肯定沒錯.
下麵是一些搜來的資料，希望對你有幫助.
動詞過去式和過去分詞的變化規則
動詞過去式和過去分詞有規則變化和不規則變化兩種.
1）規則變化
情况例詞讀音與說明
動詞原形過去式過去分詞
一般在動詞原形後加-ed look
call
open
need looked
called
opened
needed looked [lukt]
called [kC:ld]
opened [5EupEnd]
needed [ni:did]①-ed在清輔音音素後
發音為〔t〕，在濁輔音後發音為〔d〕，在母音後發音也為[d]
②-ed在〔t]、〔d〕
後發音為[id]
③但fix的過去式和過去
分詞x不雙寫，為fixed.
以-e結尾的動詞加-d move
phone
hope
agree moved
phoned
hoped
agreed moved [mu:vd]
phoned [fEund]
hoped [hEupt]
agreed [E5^ri:d]
以輔音字母加y結尾的動詞，變y為i，
再加-ed study
carry
try studied
studied
carried studied [5stQdid]
carried [5kArid]
tried [traid]
以原音字母加y結尾的詞，直接加-ed play
enjoy
stay played
enjoyed
stayed played [pleid]
enjoyed [in5dVCid]
stayed [steid]
末尾只有一個輔音字母的重讀閉音節詞，雙寫該輔音字母，再加-ed stop
plan
fit stopped
planned
fitted stopped [stCpt]
planned [plAnd]
fitted [5fitid]
以-r音節結尾的詞，雙寫r字母，
再加-ed prefer
refer pref