2 after he had worked hard many years ,he retired
before he retired , he had worked hard many years
3 she bought this book two weeks ago
she has bought this book for 2 weeks
4 we last went to the cinema two weeks ago
we haven't gone to the cinema for 2 weeks

5 lt's over ten years since we got married
we have got married for 10 years

6 l have never read such an interesting novel befor
this is the first time I read such an interesting novel
7 we had luch and then went for a walk
after we had lunch , we went for a walk
8 how long have you learnt english ?
when did you learn E ?
9 the last time l saw jim was in 2004
l haven't seen Jim since 2004
10lt 's the coldest winter they've ever had
they have never had the coldest winter before

#Yumi

Tự vẽ hình

Ta có : \(CA . CE = CD . CB\)

\(\Rightarrow\) \(\dfrac{CA}{CD} = \dfrac{CB}{CE}\)

Xét \(\bigtriangleup{CAD} \) và \(\bigtriangleup{CBE}\) , có :

\(\widehat{BCE}\) : chung

\(\widehat{CDA} = \widehat{CBE} = 90 ^0\)

\(\Rightarrow\) \(\bigtriangleup{CAD}\) ~ \(\bigtriangleup{CBE}\) ( g.g)

\(\Rightarrow\) \(\dfrac{CA}{CB} = \dfrac{CD}{ CE}\)

\(\Rightarrow\) \(CA. CE = CB . CD\) (đpcm)

b, Xét \(\bigtriangleup{AQC}\) vuông tại Q , có : \(QE \perp AD\)
Áp dụng hệ thức \(b^2 = a . b'\) , có :

\(\Leftrightarrow\) \(CQ^2 = CA . CE \) (1)

Xét \(\bigtriangleup{CPB}\) vuông tại P , có : \(PD \perp BC\)

Áp dụng hệ thức \(b^2= a . b'\)

\(\Leftrightarrow\) \(CP^2 = CB . CD \) (2)

Vì \(CA . CE = CB . CD \) (cmt) (3)

Từ (1),(2) và (3) \(\Rightarrow\) \(CQ^2 = CP^2\)

\(\Rightarrow\) \(CQ = CP \) (đpcm)

I. Rewrite these sentences

1. Where are you from? Where..DO YOU LIVE ?..

2. What is your job? What .DO YOU DO ?....

3. She likes cooking? She.IS INTERESTED IN COOKING...

4. Have you got a blck pen? Do..YOU HAVE A BLACK PEN ?.

1. Learning English is very useful.

It's very useful to learn English.

2.They spent 2 years building this villa.

It took them 2 years to build this villa.

3.He didn't hurry,so he missed the train.

If he hadn't hurry, he wouldn't have missed the train.

4.Janet is te tallest student in her class.

No one is taller than Janet in her class.

5.The car was so expensive that i didn't bye it.

The car was too expensive for me to buy.

6.We started learning english more than 6 years ago

We have learnt E for more more than 6 years.

7.I last saw him 3 day ago.

I haven't seen him for 3 days.

8.The robbers made the bank manager hand over the money.

The bank manager was made to hand over the money.

9.We won't go on holiday because we don't have enough money

If we have enough money, we will go on holiday.

10.I think you should hand in your homework on time.

If i were you, I would hand in your homework on time.

11.If you don't water the plants regularly enough,they will die

Unless you water the plants regularly enough, they will die.

FIX

3.He didn't hurry,so he missed the train.

If....HE HADN'T HURRIED,HE WOULDN'T HAVE MISSED THE TRAIN..................................................

4.Janet is te tallest student in her class.

No one...IN HER CLASS IS TALLER THAN JANET..........................................

9.We won't go on holiday because we don't have enough money

If...WE HAD ENOUGH MONEY,WE WOULD GO ON HOLIDAY.....................................................

3Fe_{nóng đỏ} +2O2\(\rightarrow\)Fe3O4

Fe3O4+ 8HCl +4H2O

FeCl2 + 2NaOH

FeCl3 + 3NaOH

4Fe(OH)2 + O +HO 4Fe(OH)3

2Fe(OH) \(\underrightarrow{to}\) Fe2O3+3H2O

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để mình giúp bạn làm câu khác ko lỗi

cảm ơn bạn

để mình sửa lại

1. Pleas don't make any noise; I'm very tired

⇒ I'd rather you didn't make any noise, I'm very tired.

Sắp xếp:

1. you/ mind/ if / I / stay / here?

⇒ Do you mind if I stay here ?

2. The concert hall / so crowded / I / see / hear / nothing.

⇒ The concert hall was so crowded that I saw and heard nothing.

3. It/ very kind / you / make friend / me.

⇒ It is very kind of you to make friend with me.