\(a,=2\sqrt{2a}+3\sqrt{2a}-4\sqrt{2a}=\sqrt{2a}\\ b,=3\sqrt{5}-3+\sqrt{5}=4\sqrt{5}-3\\ c,=\dfrac{\sqrt{3}-1+\sqrt{3}+1}{\left(\sqrt{3}+1\right)\left(\sqrt{3}-1\right)}=\dfrac{2\sqrt{3}}{2}=\sqrt{3}\\ d,=-7+5-2\cdot\dfrac{2}{3}+\dfrac{1}{3}\cdot3=-2-\dfrac{4}{3}+1=-\dfrac{7}{3}\)

1 don't have to

2 mustn't steal

3 had to go

4 have to wear 

5 must hurry

6 have had to wear

7 mustn't write

8 has to work

9 must stay

10 must get

11 have to wear

12 must leave

13 have to

14 mustn't lose

15 didn't have to

sao ko ai nói gì hết