Ví dụ 2: . Một vật dao động phát ra âm có tần số 80 Hz, một vật khác dao động phát ra âm có tần số 100 Hz. Vật nào phát ra âm bổng hơn? Vì sao?

Ví dụ 2: . Một vật dao động phát ra âm có tần số 80 Hz, một vật khác dao động phát ra âm có tần số 100 Hz. Vật nào phát ra âm bổng hơn? Vì sao?

Câu 17. Ứng dụng nào sau đây là của gương cầu lõm

A. Kính chiếu hậu xe ô tô                                  B. Kính vạn hoa

C. Kính tiềm vọng                                             D. Bếp mặt trời

Câu 10: Ta nhìn thấy trời đang nắng ngoài cánh đồng khi

A. Mắt hướng ra phía cánh đồng.

B. Cánh đồng hắt ánh sáng Mặt Trời vào mắt ta.

C. Mặt Trời chiếu ánh sáng thẳng vào cánh đồng.

D. Cánh đồng nằm trong vùng có ánh sáng.

Câu 4: Âm phát ra càng to khi:

A. Nguồn âm có khối lương càng lớn.               B. Nguồn âm có kích thước càng lớn.

C. Biên độ dao động càng lớn.                            D. Nguồn âm dao động càng mạnh.

Cho hàm số \(y=f\left(x\right)=-3x\). Tính \(f\left(\dfrac{-3}{2}\right)\), f(-1)

\(\dfrac{x-2}{3}=\dfrac{-3}{4}\)

       45. She (invite)__________________  some friends for her birthday party next week.

      46. Children shouldn’t (stay) ________________ up late.

47.  The __________ love working on their farm. (farm)

48.  What a _________ garden! (love)

49.  Ba practices (play) _____________ the guitar every day.

50.  (you/be) _________ at home tomorrow morning?

51.    He is not very                              . He never plays games. ( sport)

52.   A                                works at a school . ( teach)

53.  29. They live in a                                      house. ( love)

53.   His drawings are very                         . (beauty)

51.  The telephone ____________ gives people’s names, addresses and telephone numbers. ( list, directory, dictionary)

52.  __________ is your telephone number ? - 8765432.( What, How, Where )

53.  What’s your _________ ? – May 5th . ( date of birth, birthday , birth date )

54.  I’m sorry . Mary isn't in at the moment. Can you _______ back later? ( call, say, speak)

55.  I’d like to have your _____ . OK. 98765432. ( phone, mobile phone, address, telephone number )

56.  She is a new student , so she is __________ . ( nervous, nice, sure)

57.  Which is the _________ month of the year? – March. ( three, third, fifth)

58.  Which is the ninth month of the year ? - ___________. ( September , November, February)

59.  Her birthday is on the __________ of July. ( twelve, twelfth, twelveth)

60.  The phone is ringing. – I’ll _______ it. ( open, answer , listen)

61.  I am going to ______ a party. Would you like to come? ( start, invite, have, meet )

62.  She will _______ some of her friends to the birthday party. ( invite, have, meet, see )

63. Her father is a doctor. He works in a . . . . . . . . . . (school / hospital /factory / farm)

64. She is a teacher . She teaches in a primary . . . . . . . . . (school / hospital /factory / farm)

65. He is a . . . . . . . . . . . . . He works on a farm. ( teacher / farmer / journalist/ doctor)

14.  Minh practices (play)_______________ the guitar every day after school.

15.   The boys (play)________________ soccer at present.

16.   Students should (do) ________________ homework before class.

17.  He must be a good _________ (teach).

18.  Nam is not _________ (sport). He always watches TV and reads comics in his free time.

19.  How are your parents? – They’re very _________ (good). Thank you very much.

20.  They _________ (collector) trash along the streets on Green Sundays.

21.  I think this apartment is the most __________ for your family . (suit)

22.  That is the most ____________ armchair I have. (comfort)

23.  She feels very unhappy because she doesn’t have any ________ in this new town. (friendly)

24.  Her school is _______________ from her old one . (differ)

25.   Armchairs are more ________________________ than chairs.                       (comfort)

26.   He writes for a newspaper. He is a ________________________.                  (journal)

27.   Ba is a good stamp ________________________.                                             (collect)

28.   What a ________________________ home!                                                         (love)

29.  Jane (be)                               a famous artist one day.

30.  (you/look)                                               for Lan? I think she’s reading in the library.

31.  Would you like (see)                           a movie?

32.  She often (study)                                   maps in Geography.

33.   Hurry up! We …………………….. (wait) for you.

34.   The earth ___________ (move) around the sun.