9 D

2 A

3 C

4 D

13 D

14 C

15 C

16 D

17 C

18 C

1) $-3\sqrt{13}=-\sqrt{117}<-\sqrt{81}=-9$

3) Ta có: $5^2=25=9+16$

${\left(2\sqrt{2}+1\right)}^2=9+4\sqrt{2}$

mà $16>4\sqrt{2}$

nên $5>2\sqrt{2}+1$

1 nature

2 poems

3 His grandfather

4 competition

5 the first prize

IV

1 How far is it from here to ACB Bank?

2 How long have you known Marie?

3 Did they use to be friends at the....?

4 When did Sarah leave?

5 What is she watching?

6 What is it?

7 What does she like watching?

8 Who does it start?

9 How did you feel before your last Maths test?

10 How did she feel when she watched a ?

1 I go to school. It is near my house

=> I go to school which is near my house

2 My father bought a car. He likes it very much

=>  My father bought a car which he likes very much

3 My mother cooks dinners. They are delicious

=> My mother cooks dinners which are delicious

4 She is reading a book. She likes the book so much

=> She is reading a book which she likes so much

5 I am playing football. It keeps me fit

 I am playing football which keeps me fit

c

ĐK: $x\ge 0$

$6+\sqrt{x}-x=0$

$6+3\sqrt{x}-2\sqrt{x}-x=0$

$\iff 3(2+\sqrt{x})-\sqrt{x}(2+\sqrt{x})=0$

$\iff (\sqrt{x}+2)(3-\sqrt{x})=0$

$\iff [\begin{array}{c}\sqrt{x}+2=0\\ 3-\sqrt{x}=0\end{array}$

1 B

2 A

3 A

4 B

5 A