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