1, from

2,of, for

3,as, in

4,with, on

5,in

6, in, for

7,For

8, to, at

1. impossible

2. finally

3. determined

4. education

5. founded

em nhé!

is not different

is not different 

15.had never seen-visited

16.am doing

17.am reading

18.am still waiting

19.are they speaking

20.is stealing

21.was working-was shopping

22.was making

23.was you doing

24.was looking

25.I was looking

26.has been

27.hasn't read

28.have you drunk

29.have heard

30.has lived

38. People have to cross water to get to this i_ _ _ _ _ (điền từ ạ)

- Đáp án: island

40. Engineers build this to take things in boats from one place to another c_ _ _ _ (điền từ ạ)

- Đáp án: canal

38. island

39. canal

38 island

40 canal 

Hai tam giác vuông CAB và CFE đồng dạng (chung góc C)

\(\Rightarrow\dfrac{CF}{CA}=\dfrac{EF}{AB}=\dfrac{AD}{AB}=\dfrac{AD}{3}\)

\(\Rightarrow\dfrac{AC-AF}{AC}=\dfrac{AD}{3}\Leftrightarrow\dfrac{AC-2}{AC}=\dfrac{AD}{3}\Rightarrow AD=3\left(\dfrac{AC-2}{AC}\right)\)

\(S_{ABC}=\dfrac{1}{2}AB.AC=\dfrac{3}{2}AC\)

\(S_{ADEF}=AD.AF=2AD=6\left(\dfrac{AC-2}{AC}\right)\)

Theo đề bài: \(S_{ADEF}=\dfrac{1}{2}S_{ABC}\Rightarrow6\left(\dfrac{AC-2}{AC}\right)=\dfrac{1}{2}.\dfrac{3}{2}AC\)

\(\Leftrightarrow8\left(AC-2\right)=AC^2\Leftrightarrow AC^2-8AC+16=0\)

\(\Leftrightarrow\left(AC-4\right)^2=0\Leftrightarrow AC=4\)

Vậy \(S_{ABC}=\dfrac{1}{2}AB.AC=\dfrac{1}{2}.3.4=6\left(cm^2\right)\) \(\Rightarrow S_{ADEF}=3\)

a, 25/12

b,  25/72

a) = 3/4 + 4/3 = 25/12

b) = 3/8 - 16/9 = -101/72 * hình như hơi sai sai:"> *

8d

9c

10d

11a

12d