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So sánh
Tác dụng: so sánh công cha được ví như núi Thái Sơn rất cao to hùng vĩ ý nói người cha rất lớn lao bao nhiêu lần cha đă hi sinh cho con cái nỗi gian nan vất vả
nghĩa mẹ được ví như nước trong nguồn chảy ra rất nhiều không bao giờ hết như tình cảm của người mẹ đối với con cái mình
In this section you must choose the word or phrase which best completes each sentence. Circle the letter A, B, C or D against the number of each item 1-20 for the word or phrase you choose. (20 points)
1. My sister is very fond .................... chocolate candy.
A. of B. about C. with D. at
2. I have studied English ....................eight months.
A. for B. since C. by D. in
3. Listen ....................our teacher !
A. with B. to C. for D. in
4. There isn’t ....................food in the house.
A. none B. no C. some D. any
5. He arrives …………………..at six o’clock.
A. at home B. home C. in home D. to home
6. Herbert has had his car………………….. 1999.
A. ago B. since C. to D. for
7. How long will it ....................to get there ?
A. cost B. lose C. make D. take
8. I ....................it to you if you don’t have one.
A. give B. gave C. will give D. would give
9. ....................your homework yet ?
A. Did you finished B. Are you finishing C. Do you finish D. Have you finished
10. It’s the best book I …………………..read.
A. have ever B. had ever C. will ever D. can ever
11. He looked very..................when I told him the news.
A. happily B. happy C. happiness D. was happy
12. She is ..................in history.
A. interests B. interested C. interesting D. being interest
13. Is the Eiffel Tower taller....................Big Ben ?
A. then B. than C. as D. of
14. At school, David was..................anyone else in his class.
A. as clever as B. as clever than C. cleverer as D. cleverest
15. She speaks French ....................than you.
A. more faster B. more fluently C. well D. the most fluently
16. It began to rain while we…………………..soundly.
A. slept B. were sleeping C. have slept D. are sleeping
17. She doesn’t coffee, does she ?
A. Yes, she doesn’t B. No, she does C. Yes, she did D. No, she doesn’t
18. I won't go to bed …………………..I finish my homework.
A. until B. when C. while D. since
19. Is this book ………………….. ? Yes, it's mine.
A. you're B. yours C. you D. your
20. …………………..do you come to school ? By bus
A. How B. What C. By D. When
Bài 2
a)
Giả sử \(a\le b\le c\)
Xét 3 trường hợp
TH1:Nếu a=2,b=3,c=5 thì \(a^2+b^2+c^2=38\)(không phải số nguyên tố) (1)
TH2:Nếu a=3,b=5c=7 thì \(a^2+b^2+c^2=83\) (t/m) (2)
TH3: a,b,c >3 => \(a,b,c⋮̸3\)
\(\Rightarrow a^2\equiv1\left(mod3\right)\); \(b^2\equiv1\left(mod3\right)\); \(c^2\equiv1\left(mod3\right)\)
\(\Rightarrow a^2+b^2+c^2\equiv3\left(mod3\right)\)\(a^2+b^2+c^2⋮3\)
Từ (1),(2),(3) ta suy ra có 3 số duy nhất cần tìm là 3,5,7