Cho biết Cu có 2 đồng vị ⁶⁵Cu(27%), ⁶³Cu(x%). Nguyên tử khối trung bình có đồng vị là 63,54. Tính thành phần phần trăm số nguyên tử của mỗi đồng vị.

1. Mary has not drunk Coca cola before.

-->It is

2.They have not cleaned the door for 2 weeks.

-->The last time..

-->They last ..

-->It is….

3. Peter has learned to swim for 1 month.

-->Peter started ..

4. They have not met their parents for 2 moths

-->The last time…

-->They last ..

-->It is

5. The coffee is very hot. I can’t drink it.

-->The coffee is

6. He is very young. He can’t understand this problem.

-->He is …

1. I have not gone to the beach for 2 months

The last time…..

I last ..

It is ..

2.The little girl has not seen such a big elephant before.

It …

3. They have played tennis for 3 years.

They started….

4. I started working here in 1998.

I have ……………………………………………………….

5. During my stay in Paris, I met my wife.

While …

6. He doesn’t grow tulips any more

He ….

7. My teacher lives in Qn city. Her daughter is my classmate. ( relatuve clause)

My teacher …

1)   Tom gave up  smoking  two years ago.

-->Tom used ……………………………………….

2)   I quite like drinking coffee in the morning, although I wasn’t keen on it when I was young.

--> I didn’t ………………………………………….

3)   My father took me to school when I was a child .

--> My father used …………………………………………

4)   He often played tennis when he was young .

--> He used ……………………………..

5)   I usually ate ice scream when I was a child , but now I don’t  any longer.

-->  I used ……………………………………..

1)   She watched the film , then she wrote a report.

--> After ………………………..

2)   The workers finished their work , and then they went out for dinner.

-->Before…………………..

3)   When you phoned me , it was my lunch time.

-->I was ……………………………..

4)   I haven’t been to the cinema for two months.

-->The last time……………………………..

5)   They will spend two years building the house.

-->It will take ……………………………..

6)   Steve started working for this company five years ago.

-->Steve has………………………………….

7)   Mac  Kenzie wrote four best-sellers before he was twenty.

-->By the age……………………………………

8)   The decorators have finished the whole of the first floor.

-->We have………………………………………

9)   You can try to get Jim to lend you his car , but you won’t succeed.

-->There’s no point……………………………

10)              I’ll  finish the work tonight if you like.

-->Would you like ………………………………………?

1/The burglar escaped , and then the police arrived.

-->Before .......................................

2/Before he went to shool , he had ironed his clothes.

-->First...............................................

3/ He had hardly left the office when the telephone rang.

-->No sooner...................................................

4/I had only just put the phone down when the boss rang back.

-->Hardly................................

5/As soon as I got into the bath , someone knocked at the door.

-->No sooner.............................

6/Just as she put the phone down, it rang again.

-->Barely...............................................

7/He got down to writing the letter as soon as e returned from his walk.

-->No sooner............................................

8/ She had hardly begun to speak before people started interrupting her .

-->Hardly...................................

9/Sam played tennis yesterday and it as his first game.(never)

-->...............................

10/Sam is playing tennis now and it is his first game.(never)

-->.................................................

11/How long is it since they went to Nairobi?(When)

-->..........................................

12/Mac Kenzie wrote four best-sellers before he was twenty. (By the age )

-->...................................................

13/Alice made an appointment, and went to see the doctor.

-->After.......................................................

( Mong mọi người giải dùm với, và có thể giải thích đính kèm theo đc ko ạ . CẢM ƠN MỌI NGƯỜI TRC )

Exercise 5/ Rewrite the following sentences.

1. I met her during my stay in Paris last summer.

--->While..........................

2.In the middle of our dinner there was a knock at the door .

-->While we ..............................

3.At 8o'clock last night , my father was watching football. At the same time, my mother was washing the dishes.

-->While...............................................

4. First he booked the restaurant, and then he invited everybody.

-->Before..........................................

5. The workmen finished , and then Mr Jackson came home.

-->After......................................................