Bài 15:
Vì `CD` là tia phân giác của \(\hat{ACB}\)
`=>` \(\hat{ACD}=\hat{DCB}=20^{o}\)
mà \(\hat{ACB}=\hat{ACD}+\hat{DCB}\)
nên \(\hat{ACB}=20^{o}+20^{o}\)
\(\hat{ACB}=40^{o}\)
b, Vì \(\hat{xAB}\) và \(\hat{BAC}\) là 2 góc kề bù
`=>` \(\hat{xAB}+\hat{BAC}=180^{o}\)
\(\hat{xAB}=180^{o}-\hat{BAC}\)
\(\hat{xAB}=180^{o}-70^{o}\)
\(\hat{xAB}=110^{o}\)
mà `AD` là tia phân giác góc \(\hat{xAB}\)
Suy ra \(\hat{A1}=\hat{A2}=\frac{\hat{xAB}}{2}=\frac{110^{o}}{2}=55^{o}\)

1. Look! The bus _______.
A. comes B. is coming C. came D. coming
2. My father usually _______ coffee in the morning.
A. drinks B. drink C. is drinking D. drank
3. Yesterday, they _______ to the cinema together.
A. go B. goes C. went D. are going
4. Listen! Someone _______ the piano.
A. plays B. is playing C. played D. play
5. I _______ a student ten years ago.
A. am B. was C. were D. are
6. Where _______ you live now?
A. do B. does C. did D. are
7. She _______ her homework at the moment.
A. does B. do C. is doing D. did
8. Last night, we _______ a terrible noise outside.
A. hear B. hears C. heard D. are hearing
9. The sun _______ in the East.
A. rise B. rises C. is rising D. rose
10. Look at them! They _______ photos.
A. take B. takes C. are taking D. took
11. Why _______ you cry last night?
A. do B. does C. did D. are
12. Water _______ at 100 degrees Celsius.
A. boils B. boil C. is boiling D. boiled
13. Don't make noise! The baby _______.
A. sleeps B. is sleeping C. slept D. sleep
14. Two years ago, he _______ English in London.
A. studies B. study C. studied D. is studying
15. Every Sunday, my mom _______ to the market.
A. go B. goes C. is going D. went
16. I _______ a letter to my friend right now.
A. write B. am writing C. wrote D. writes
17. We _______ our grandparents last weekend.
A. visit B. visited C. are visiting D. visits
18. He _______ soccer very well. He is a professional player.
A. play B. plays C. is playing D. played
19. Keep silent! The teacher _______.
A. speaks B. speak C. is speaking D. spoke
20. They _______ buy that car yesterday because it was too expensive.
A. don't B. doesn't C. didn't D. aren't
21. Cats _______ mice.
A. catch B. catches C. catching D. caught
22. What _______ you doing at the moment?
A. do B. does C. did D. are
23. When I was young, I _______ to be a doctor.
A. want B. wants C. wanted D. am wanting
24. She _______ eat meat. She is a vegetarian.
A. don't B. doesn't C. didn't D. isn't
25. Hurry up! Everyone _______ for you.
A. waits B. wait C. is waiting D. waited
26. I _______ my keys this morning. Now I can't find them.
A. lose B. lost C. am losing D. loses
27. My brother _______ like science fiction movies.
A. don't B. doesn't C. didn't D. isn't
28. The earth _______ around the sun.
A. go B. goes C. is going D. went
29. _______ you watch the football match last night?
A. Do B. does C. Did D. Are
30. They _______ in the garden right now.
A. work B. works C. are working D. worked
31. Shakespeare _______ many famous plays.
A. write B. writes C. wrote D. is writing
32. Rice _______ in warm climates.
A. grow B. grows C. is growing D. grew
33. She _______ a beautiful dress today.
A. wear B. wears C. is wearing D. wore
34. We _______ a new house last month.
A. buy B. buys C. bought D. are buying
35. _______ it rain a lot in summer?
A. Do B. Does C. Did D. Is
36. Look! The birds _______ in the sky.
A. fly B. flies C. are flying D. flew
37. I _______ see you at the party last Friday.
A. don't B. doesn't C. didn't D. wasn't
38. He always _______ up early.
A. get B. gets C. is getting D. got
39. Listen to those people! What language _______ they speaking?
A. do B. does C. did D. are
40. Christopher Columbus _______ America in 1492.
A. discover B. discovers C. discovered D. is discovering
41. I usually _______ to bed before 10 PM.
A. go B. goes C. am going D. went
42. My sister _______ cooking dinner in the kitchen now.
A. does B. is C. did D. was
43. They _______ very happy at the concert last night.
A. are B. was C. were D. did
44. Vegetarians _______ eat meat.
A. don't B. doesn't C. didn't D. aren't
45. The leaves _______ red and yellow in autumn.
A. turn B. turns C. are turning D. turned
46. Look! That man _______ to open your car door.
A. tries B. try C. is trying D. tried

`222+778+543+654+457+346+123`
`=(222+778)+(543+457)+(654+346)+123`
`=1000+1000+1000+123`
`= 3. 1000+123`
`=3000+123`
`=3123`

`81279-(64102-4102)`
`=81279-60000`
`=21279`

1. A. Windy B. Sunny C. Box D. Cold
2. A. Cake B. Chips C. Food D. Pizza
3. A. Nine B. Egg C. Four D.Ten

Mục đích của Hội Duy Tân vào đầu những năm 1900 là đánh đuổi thực dân Pháp, giành độc lập cho dân tộc và xây dựng một nước Việt Nam độc lập dưới chế độ quân chủ do Cường Để đứng đầu.