24 Yes,they do

Còn lại đúng hết rồi nhé

1. playing

2. listening

3. getting

4. seeing

7. exceeding

9. reading

10. stepping

11. be

12. to contact

13. to lose

14. to hear

15. phoning/going

16. Lying/sitting

19. to help/to choose

20. to learn/ listening

21. to wait

22. to come

23. stay/ to annoy

24. borrowing/ asking

25. to send

26. to tell/ looking

28. answer

29. to send

30. answering/ ring

15: Pha dao động là pi+pi/2=3/2pi

=>Chọn C

14:

Khi t=1,25 thì \(x=2\cdot cos\left(2.5pi-\dfrac{pi}{6}\right)=1\)

=>Chọn A

15: Pha dao động là pi+pi/2=3/2pi

=>Chọn C

14:

Khi t=1,25 thì \(x=2\cdot cos\left(2.5pi-\dfrac{pi}{6}\right)=1\)

=>Chọn A

16: \(10t-\dfrac{3}{2}pi=\dfrac{2}{3}pi\)

=>10t=2/3pi+3/2pi=13/6pi

=>t=13/60pi

\(x=6\cdot cos\left(10\cdot\dfrac{13}{6}pi-\dfrac{3}{2}pi\right)\)

\(=6\cdot cos\left(\dfrac{2pi}{3}\right)=-3\)

=>Chọn C

theo anh tối thiểu 2

chỉ cần 1 mẫu thử là Ba(OH)2

PTHH: 2NaOH + H₂SO₄ ---> Na₂SO₄ + 2H₂O

Ta có: \(C_{\%_{NaOH}}=\dfrac{m_{NaOH}}{100}.100\%=20\%\)

=> m_NaOH = 20(g)

=> n_NaOH = \(\dfrac{20}{40}=0,5\left(mol\right)\)

Theo PT: \(n_{H_2SO_4}=\dfrac{1}{2}.n_{NaOH}=\dfrac{1}{2}.0,5=0,25\left(mol\right)\)

=> \(m_{H_2SO_4}=98.0,25=24,5\left(g\right)\)

Có thể đề sai nhé

\(4^{15}.5^{30}=\left(2^2\right)^{15}.5^{30}=2^{30}.5^{30}=\left(2.5\right)^{30}=10^{30}\)

\(4^{15}.5^{30}=\left(4.5\right)^{15}.5^{15}=20^{15}.5^{15}=\left(20.5\right)^{15}=100^{15}\)

\(=100000000000000................0000000000\)

              |30 chữ số 0|

35 A => on the flip side

36 A => in

37 C => have been derived 

38 D => tremediously

39 B => becomes 

40 D => of which

41 C => minority languages

42 C => lie under 

43 B => happens 

44 B => percent

45 C => have been born

46 B=> of whom

47 C => as well as 

48 A bỏ đi

49 C => ethnicity

50 C => sacrificing