1.The young girl who lives next door are➞is very kind to me.

2.I like the teacher who I'm learning English with her(bỏ) at high school.

3.Mr. Smith, who are➞is a retired teacher, does volunteer work at the hospital.

4.I have two sisters which➞are are doctors.

5.The banker who I gave my check to him(bỏ) was quite friendly.

6.The young woman who lives next door is very kind with➞to my family.

7.What are➞is the name of the man who lent you money?

8.This is the best play which(bỏ) I’ve ever seen.

9.I know a nearby restaurant which➞that sell seafood.

10.Mr. John, which➞who I was working for, was generous with overtime payments.

C

C

B

- Ta có: P là trung điểm của BC (gt) => BP=CP

- Xét △ABP có:

 + M và I là trung điểm của AB và AP => \(IM//BP\) ; \(IM=\dfrac{BP}{2}\)

- Xét △ACP có:

 + I và N là trung điểm của AP và AC => \(IN//CP\) ; \(IN=\dfrac{CP}{2}\)

- Mà \(BP=CP\) => \(\dfrac{BP}{2}=\dfrac{CP}{2}\) hay: \(IM=IN\left(1\right)\)

- △AIN và △APC có:

\(\dfrac{IA}{AP}=\dfrac{IN}{CP}\)

\(\dfrac{IN}{CP}=\dfrac{1}{2}\) \(\left(IN=\dfrac{CP}{2}\right)\)

=> \(\dfrac{IA}{AP}=\dfrac{1}{2}\)

Mà: \(AP=IA+IP\)

hay: \(1=\dfrac{1}{2}+AP\)

=> \(AP=\dfrac{1}{2}\)

=> \(IA=IP\)  hay I là trung điểm của AP (2)

Từ (1); (2). Vậy: I là trung điểm chung của MN và AP (đpcm)

\(a^2+9-6a\)

\(=a^2-6a+9\)

\(=a^2-2.a.3+3^2\)

\(=\left(a-3\right)^2\)

7/ Ta có:

- \(A_2O_3\) có \(PTK=160đvC\)

- Mà \(O_3=16\cdot3=48đvC\)

\(=>A=\dfrac{160-48}{2}=56đvC\)

Vậy: Nguyên tố A là: Sắt, kí hiệu \(Fe\)

8/ Ta có:

- \(A_2CO_3\) có \(PTK=106đvC\)

- Mà \(CO_3=12+16\cdot3=60đvC\)

\(=>A=\dfrac{106-60}{2}=23đvC\)

Vậy: Nguyên tố A là Natri, kí hiệu \(Na\)

1. ➞This flower is watered by my father every morning.

2. ➞Fiona was invited to John's birthday last night.

3. ➞The dinner is being prepared in the kitchen by her mother.

4. ➞Our teeth should be cleaned twice a day.

5. ➞The English grammar has been explained by our teacher.

6. ➞The accident was caused in the city by some drunk drivers.

7. ➞Tom's parents will be visited by him next month.

8. ➞The secretary wasn't phoned by the manager.

9. ➞Was this beautiful dress worn by Mary?

10. ➞These old pictures won't be hung in the living room.

11. ➞This factory wasn't built by the German during The Second World War.

12. ➞This house and these cars are being painted by The Greens for Christmas Day.

13. ➞The cats had been fed by Ann before she went to the cinema.

14. ➞The pollution problems have been discussed by the students since last week.

15. ➞Have the most valuable painting been stolen in the national museum by the thieves?

16. ➞The new president will be interviewed on TV.

17. ➞How many languages are spoken in Canada?

18. ➞Are those shoes being repaired?

19. ➞His nose has been broken in a football match.

20. ➞Have the above sentences been finished?

Ta có: \(\hat{A}+\hat{B}+\hat{C}+\hat{D}=360\text{°}\)

            \(\hat{\dfrac{A}{1}}=\hat{\dfrac{B}{2}}=\hat{\dfrac{C}{3}}=\hat{\dfrac{D}{4}}\)

- Áp dụng tính chất của dãy tỉ số bằng nhau ta được:

\(\hat{\dfrac{A}{1}}+\hat{\dfrac{B}{2}}+\hat{\dfrac{C}{3}}+\hat{\dfrac{D}{4}}=\dfrac{\hat{A}+\hat{B}+\hat{C}+\hat{D}}{1+2+3+4}=\dfrac{360\text{°}\text{​​}}{10}=36\)

=> \(\hat{A}=36.1=36\text{°}\)

     \(\hat{B}=36.2=72\text{°}\)

     \(\hat{C}=36.3=108\text{°}\)

     \(\hat{D}=36.4=144°\)

a/ Chứng minh:

\(\left(x+a\right)\left(x+b\right)\)

\(=x^2+bx+ax+ab\)

\(=x^2+\left(ax+bx\right)+ab\)

\(=x^2+x\left(a+b\right)+ab=VP\) (đpcm)

b/ Chứng minh:

\(\left(x+a\right)\left(x+b\right)\left(x+c\right)\)

\(=\left(x^2+ax+bx+ab\right)\left(x+c\right)\)

\(=x^3+cx^2+ax^2+acx+bx^2+bcx+abx+abc\)

\(=x^3+\left(ax^2+bx^2+cx^2\right)+\left(abx+bcx+acx\right)+abc\)

\(=x^3+x^2\left(a+b+c\right)+x\left(ab+bc+ac\right)+abc=VP\) (đpcm)