请用spend on 造一个句子,再用spend in doing进行同义句转换

cost主语为物,一般为 it cost sb.some money
spend,指花费时间,spend doing; spend on sth.
take,指时间或金钱 take some money
pay for,指金钱,指为.付帐 pay for dinner / pay for bill
take,spend ,cost ,pay的用法都可以表示“花费”,但用法却不尽相同.
spend的主语必须是人,常用于以下结构：
(1) spend time ／money on sth.在……上花费时间（金钱）.
例：I spent two hours on this maths problem.这道数学题花了我两个小时.
(2) spend time ／ money (in) doing sth.花费时间（金钱）做某事.
例：They spent two years (in) building this bridge.造这座桥花了他们两年时间.
(3)spend money for sth.花钱买…….
例：His money was spent for books.他的钱用来买书了.
cost的主语是物或某种活动,还可以表示“值”,常见用法如下：
(1)sth.costs (sb.) ＋金钱,某物花了（某人）多少钱.
例：A new computer costs a lot of money.买一台新电脑要花一大笔钱.
(2) (doing) sth.costs (sb.) ＋时间,某物（做某事）花了（某人）多少时间.
例：Remembering these new words cost him a lot of time.他花了大量时间才记住了这些单词.
注意：cost的过去式及过去分词都是cost,并且不能用于被动句.
take后面常跟双宾语,常见用法有以下几种：
(1) It takes sb.＋时间＋to do sth.做某事花了某人多少时间.
例：It took them three years to build this road.他们用了三年时间修完了这条路.
(2)doing sth.takes sb.＋时间,做某事花了某人多少时间.
例：Repairing this car took him the whole afternoon.他花了一下午修车.
pay的基本用法是：(1) pay (sb.) money for sth.付钱（给某人）买…….
例：I have to pay them 20 pounds for this room each month.我每个月要付20英磅的房租.(2)pay for sth.付……的钱.例：I have to pay for the book lost.我不得不赔丢失的书款.
(3)pay for sb.替某人付钱.例：Don't worry!I'll pay for you.别担心,我会给你付钱的.
(4)pay sb.付钱给某人.例:They pay us every month.他们每月给我们报酬.
（5）pay money back 还钱.
例：May I borrow 12 yuan from you?I'll pay it back next week.你能借给我12块钱吗?下周还你.

spend money on sth
spend time in doing sth
It's right

I usually spend two hours on playing games

pay for something 为什么买单
spend something(钱或时间) on something 在什么上花费什么
这句话如果用后者就会缺少宾语,所以是paid fo

It takes somebody (time/money)to do something.
Something cost somebody(time/money).

just spend on them who really in need rather.
与其把钱花在不必要的事情上,倒不如把钱花在真正需要的地方.
How long did the workers spend on building this hospital?
工人们建成这座医院花费了多长时间?
How long does he spend on English study every day?
他每天在英语（学习）上花多长时间?
http://dict.youdao.com/search?q=lj%3Aspend+on&btnindex=%E6%90%9C+%E7%B4%A2&ue=utf8&keyfrom=dict.moresentence
I spend 10 minutes in doing my homework every day.
我每天花10分钟做作业.
http://dict.youdao.com/search?tab=chn&keyfrom=dict.moresentence&q=lj%3Aspend+in+doing&btnG=%E6%90%9C+%E7%B4%A2

1)spend的主语必须是“人”,宾语可以是钱,精力,时间等,其后用on(for)+名词或用in(可省略)+动名词形式,不接不定式.如：
He spent a lot of money for his new car.
他花了很多钱买了这辆新车.
He spends much money on books.
他平时将很多钱用在买书上.
Mr Li spends a lot of time(in)helping his students with their English.
李老师花很多时间帮助他的学生学英语.
2)cost可用于表示花时间和金钱,其主语一般是“物”或“事”,表示“费用”、“耗费”.如：
The book cost him one dollar.这本书用了他一美元.
Homework costs the children much time.家庭作业要花孩子们许多时间.
注意：cost与表示时间的词连用时,不能与具体时间长度连用,只能与表示抽象概念的时间短语(如some time,much time等)连用.

很少见 spend time in doing sth 这种说法.
一般而言,spend time 后如果直接跟“动名词”（v+ing）,既不用 in 也不用 on.
如果后面跟的是地点状语,用 in；如果跟的是事或人,用 on.例：
My parents spent their vacation in Paris.
I spent all my resources on futile projects.
John spent most of his time on his girlfriend.

当作花费时间或金钱时,后面接on后用名词

可以
spend (time/money )on sth.
spend (time/money )in doing sth.

spend的主语必须是人,常用于以下结构：
(1) spend time ／money on sth. 在……上花费时间(金钱).例：
I spent two hours on this maths problem. 这道数学题花了我两个小时.
(2) spend time ／ money (in) doing sth. 花费时间(金钱)做某事.例：
They spent two years (in) building this bridge. 造这座桥花了他们两年时间.
(3)spend money for sth. 花钱买…….例：
His money was spent for books. 他的钱用来买书了.
cost的主语是物或某种活动,还可以表示"值",常见用法如下：
(1)sth. costs (sb.) ＋金钱,某物花了(某人)多少钱.例：
A new computer costs a lot of money. 买一台新电脑要花一大笔钱.
(2) (doing) sth. costs (sb.) ＋时间,某物(做某事)花了(某人)多少时间.例：
Remembering these new words cost him a lot of time. 他花了大量时间才记住了这些单词.
注意：cost的过去式及过去分词都是cost,并且不能用于被动句.
take后面常跟双宾语,常见用法有以下几种：
(1)It takes sb. ＋时间＋to do sth. 做某事花了某人多少时间.例：
It took them three years to build this road. 他们用了三年时间修完了这条路.
(2)doing sth. takes sb. ＋时间,做某事花了某人多少时间.例：
Repairing this car took him the whole afternoon. 他花了一下午修车.
pay的基本用法是：
(1) pay (sb.) money for sth. 付钱(给某人)买…….例：I have to pay them 20 pounds for this room each month. 我每个月要付20英磅的房租.
(2)pay for sth. 付……的钱.例：
I have to pay for the book lost. 我不得不赔丢失的书款.
(3)pay for sb. 替某人付钱.例：
Don’t worry! I'll pay for you. 别担心,我会给你付钱的.
(4)pay sb. 付钱给某人.例:
They pay us every month.他们每月给我们报酬.
(5)pay money back 还钱.例：
May I borrow 12 yuan from you? I'll pay it back next week. 你能借给我12块钱吗?下周还你.
(6)pay off one's money还清钱.

可以
I have spent 50 yuan on the book
=I have paid 50 yuan for the book


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We spend much time and money on new course

spend...on 一般后面只跟名词,如：
He spent 3 days on the work.
同样的意思,如果用spend...(in) doing sth.来表达,那就是：
He spent 3 days doing the work.
这两个句型都用于”花多少时间用于某事“,只不过一个后面直接跟名词,另一个跟动名词

Many students spend so much of their spare time on computer games.It will do harm to their health.So more and more parents have paid much attention to this problem.They are worring about the serious problem.The begin to notice the importance to control their children's time on playing computer games.

spend on
把…花在…
He doesn't spend much time on his homework.
他花在作业上的时间不多.
spend
1 【MONEY】 [I and T]
to use your money to pay for goods or services
I can't afford to spend any more money this week.
spend £5/$10 etc
I only want to spend about $20.
spend sth on sth
More money should be spent on education.
spend sth on sb
Mum never spends any money on herself.
The repairs cost a lot,but it's money well spent (=a sensible way of spending money) .
2
【TIME】 [T]
to use time doing a particular thing or pass time in a particular place
spend time etc with sb
I want to spend more time with my family.
spend time etc in/at sth
We'll have to spend the night in a hotel.
His childhood was spent in Brazil.
spend time etc doing sth
Stacey spends all her free time painting.
其实,spend与spend on的差别不大
如果要真的清晰的分清他们,的找出具体的题

不能.因为用how long提问的句子,回答时候要用介词for...表示一段时间.
比如-How long have you watched TV?
-I have watched TV for two hours.

spend on在某物上花费：spend on doing sth
spend for为某物花费 :spend for sth
两者意思相近.
至于spend（花费）与invset（拜访）的区别,我真还不知道.