tính khoảng cách giữa kim giờ và kim phutscuar 1 đồng hồ lúc 2 giờ biết kim giờ dài 2cm kim phút dài 4cm

bài 39 40 41 43 44 . MN LÀM ƠN GIÚP VỚI!

GIÚP MK VỚI 

Bài 4: Cho 15,5g Na₂O tác dụng với nước thu được 0,5 lit dd bazơ.

a.     Tính C_M của dd thu được

b.    Tính V_dd H₂SO₄ nồng độ 20% (D= 1,14g/ml) cần dùng để trung hoà dd bazơ thu được.

c.     Tính C_M các chất có trong dd sau phản ứng trung hoà.

Bài 5: Có hỗn hợp gồm bột Fe và bột kim loại M có hoá trị n. Nếu hoà tan hết hỗn hợp này trong dd HCl, thu được 7,84 lít khí H₂ (đktc). Nếu cho hỗn hợp trên tác dụng với khí Cl₂ thì thể tích khí Cl₂ cần dùng là 8,4 lit (đktc). Biết tỉ lệ số nguyên tử Fe và kim loại M là 1:4.

a.     Viết các PTHH xảy ra

b.    Tính thể tích khí Cl₂(đktc) đã hoá hợp với kim loại M

c.     Xác định hoá trị n của kim loại M

d.    Nếu khối lượng M có trong hỗn hợp là 5,4g thì M là kim loại nào?

giúp với 

nhờ mn gải giúp 22 23 :))

trình bày ra

\(\sqrt{27.48\left(1-a\right)^2}vớia>1\)                            \(\dfrac{1}{a-b}.\sqrt{a^4\left(a-b\right)^2}\) với a > b

REVISION ON VERB TENSES

1. ............................ (you/have)  a nice time in Rome?

2. ............................ (you/finish)  your homework yet?

3. He (be)........................ at his computer for six hours.

4. How many people (die)................... in the fire yesterday?

5. I (not/know).................... much about art, but I like some artists.

6. I (wait)...................... for ages when finally the bus arrived.

7. I (receive)....................... a postcard from Jane yesterday.

8. I (never/be).................. sailing, what’s it like?                

9. It was late.  Most of the shops (close)..................... .

10. It (rain)...................... when I got up this morning.

11. Janet (start)................... a new job in September.

12. Nelly (have) ........................ a great time in New York at the moment.

13. She was cooking dinner when we (arrive)....................  .

14. She (just/come) ....................... back from a Mediterranean cruise.

14. When I got the airport I realized I (forget)....................my passport.

15. As soon as they (arrive).....................we had dinner.

16. When they were driving home last night they (see)..............a terrible accident.

17. Where ...............................(Robert/live) now?

18. Who (Mandy/talk)..... …. ..........to?

19. What would he have done if he (be)………..……. there?

20. I am very sorry but I (not finish) …………….…….  reading the book yet.

21. She (be)…..………. ill since last Monday. She won’t be able to go to the sea-side next week-end.

22. I decided to learn Greek while we (live)………………… in Delphes.

23. They were going to town when I (see)………….. them this morning.

24. If  I (bump) ………….. into a ghost, I think I would run away fast or scream.

25. He was caught after he (wander)……………… in the eastern Highlands all night.

26. We know he (buy)………..…….. a new house in a small lane quite recently, but we don’t know whether he has sold his old house.

27. I have never seen him again since I (leave)…………… Australia in 1964.

28. Who is this lady? She (move)…………… into No 4 last month.

29. This hotel is empty, it (not live)…………..…. in for a long time.

30. Yesterday afternoon he (have)……..……… a nap in the garden chair when a boy dropped a ball on his head.

31.It’s the first time I …………….(eat) this.

32This is the worst storm I ……………(ever see).

33. It was the first time I ……………………(ever see) such a beautiful girl.

34. It was the most exciting film I …………………(ever see).

35. This was the dirtiest looking dog I ……………….(ever see).

36.My friend…………….. (not see) me for many years when I ……… (meet) him last week.

37.After John………………… (wash) his clothes, he (begin) ………….to study.

38.She came into the room when they ……………….(watch) television.

39.As soon as we find another apartment, we ………………. (move).

40.She …………… (play) the piano when our guests ………… (arrive) last night.

41. My mother ………… (come) to stay with us next weekend.

42. Violets ……….. (bloom) in the spring.

43. We …………….. (not live) in England for the last two years.

44. I never ……..…….. (forget) what you just ……….. (tell) me.

45.They …………….….. (prepare) the Christmas dinner today.

46. I didn’t know what time it ……….. (be), so I ……….. (turn) on the radio.147. She says that she ……….. (live) in the country when she ……….. (be) a child.

48. When the teacher came in, the pupil ……………... (play).

 49. Mary ____________(not/eat) meat. She is a vegetarian.

·            They (go) ___________home after they (finish) _____________ their work.

·            In my country, it often (snow) ________a lot in winter.

·            My father _________(be) an engineer. He __________(work) for the company.

·            She (win) ________ the gold medal in 1986

·            Mary and Mr. Steve ________(come) from england. They _______(are) my close friends.

·            What time you _______________(have) lunch everyday?

·            When he came to the stadium, the match (already/ begin)_______________.

·            She ________(run) downstairs and opened the front door.

·            It __________(rain) a lot yesterday evening, so I ________(get) wet.

·            I _____________(just/finish) writing this book . I feel very happy.

·            Yesterday, John (go) ______________to the store before he (go) ____home.

·            He has written the report for three days. He ________________(write) its conclusion now.

·            Peter and I _____________(be) in front of the computer since 7 o’clock.

·            She used to be a winner. She __________(win) the first prize five years ago.

·            We ____________(fly) to New York since last summer.

·            Before I (watch) __________TV, I (do) ________________ my homework.

·            She ________(like) cooking. She ____________(cook) now.

·            She ______________(learn) piano for three months.

·            I ______________(receive) a letter from my old friend last week.

·             She _________(wash) cloth twice a week.

·            We ____________(do) exercise 2A on page 20 right now.

·            Look! It ______________(rain) heavily.

·            . After they (go)____________,I (sit) _________ down and (rest)________.

·            They _______________(watch) TV at 4:00 p.m yesterday.

·            He _________(open) the door, __________(enter) the room, and _________(break) something.

·            After I (wash)______________my clothes, I (sleep) ___________

·            The earthquake ______________(happen) while we ______________(sleep)

·            He _________(write) the textbook, when we ____________(have) a headache.

·            They ____________(live) in the countryside for 15 years.

·            I _____________(play) guitar since I was a boy.

·            If I (not work) _______________ at night, I would have attended the evening classes.

·            I ___________(be) there tomorrow morning.

·            We ___________(return) from New York by train.

·            He ___________(listen) to romantic music at the moment.

·            If you visit me tomorrow, I ___________(give) ou a small present.

·            No sooner (have)_________I (watch)____________TV than the phone rang.

·            They ___________(look) at the pictures when I ____________(break) the glass.

·            We ____________(study) when she ___________(call) her children.

·            He told me he (not/eat)_____________________ such kind of food before.

·            In all the world, there (be) __________ only 14 mountains that (reach) __________above 8,000 meters.

·            2. He sometimes (come) __________ to see his parents.

·            3. When I (come) __________, she (leave) __________for Dalat ten minutes ago.

·            4. My grandfather never (fly) __________ in an airplane, and he has no intention of ever doing so.

·            5. We just (decide) __________ that we would undertake the job.

·            6. He told me that he (take) ____________ a trip to California the following week.

·            7. I knew that this road (be) __________ too narrow.

·            8. Right now I (attend) __________ class. Yesterday at this time I (attend) __________class.

·            9. Tomorrow I (leave) _____________________ for home.

·            10. Margaret was born in 1950. By last year, she (live) _______________on this earth for 55 years .

·            11. The traffic was very heavy. By the time I (get) _____________to Mary’s party, everyone already (arrive) __________________

·            12. I (graduate) __________________  next month.

·            13. I (visit) __________ my uncle’s home regularly when I (be) __________ a child.

·            14. That book (be) __________ on the table for weeks. _________ you (not read) __________ it yet ?

·            15. David just (repair) __________ the TV set.

·            16. _________ you (be) __________here before? Yes, I (spend) __________ my holidays here last year.

·            17. We never (meet) __________ him. We don’t know what he (look) __________ like.

·            18. I think he (come) ____________ tomorrow.

·            19. On arriving at home I (find) __________that she just (leave) __________a few minutes before.

·            20. When we arrive in London tonight, it probably (rain) __________.

·            21. It (rain) ___________ hard now. We can’t do anything until it (stop) ________

·            22. Last night we (watch) __________TV when the power (fail) __________.

·            23. That evening we (stay) __________up to talk about the town where he (live) __________for some years.

·            24. I (sit) __________down for a rest while the shoes (repair) ______________.

·            25. Half way to the office Paul turned round and (go) __________back home because he (forget) __________to turn the gas off.

·            26. London (change) __________a lot since we first came to live here.

·            27. While we (talk) _____________on the phone the children (start) __________fighting and (break) __________a window

·            28. He used to talk to us for hours about all the interesting things he (do) __________ in his life.

·            29. You know she (stand) ____________looking at that picture for twenty minutes.

·            30. I (spend) __________ a lot of time travelling since I (get) __________this new job.

·            31. When we were at school we all (study) __________Latin.

·            32. When I (meet) __________ him , he (graduate) _____________________.

·            33. After he (finish) _____________ breakfast he (sit) __________down to write some letters.

·            34. She (have) __________a hard life, but she’s always smiling.

·            35. I think Jim (be) __________ out of town. 

\(\sqrt{x^2-2}>1\)

x-\(\sqrt{x-0.5}\) >0