5 B

6 A

7 B

8 C

9 D

10 C

11 B

12 D

13 B

14 D

1 . with

2 . turn on

3 . who

4 . largest

5 . preventing

6 . expect

7 . was wearing

8 . Thanks to

9 . available

10 . Don't forget to bring along a raincoat

Câu 1: 

\(\dfrac{2}{5}-\dfrac{1}{4}+\dfrac{3}{10}=\dfrac{8}{20}-\dfrac{5}{20}+\dfrac{6}{20}=\dfrac{8-5+6}{20}=\dfrac{9}{20}\) 

Câu 2:

\(\dfrac{-2}{5}:\left(1-\dfrac{1}{10}\right)=\dfrac{-2}{5}:\dfrac{9}{10}=\dfrac{-2}{5}.\dfrac{10}{9}=\dfrac{-2.10}{5.9}=\dfrac{-20}{45}=\dfrac{-4}{9}\) 

Câu 3:

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}=\dfrac{7}{18}+\dfrac{1}{5}=\dfrac{53}{90}\) 

Câu 4:

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\) 

\(=\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\) 

\(=\dfrac{2}{7}.1\) 

\(=\dfrac{2}{7}\)

Câu 1

\(\dfrac{2}{5}\)-\(\dfrac{1}{4}\)+\(\dfrac{3}{10}\)= \(\dfrac{8}{20}\)-\(\dfrac{5}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{3}{20}\)+\(\dfrac{6}{20}\)=\(\dfrac{9}{20}\)

Câu 2

-\(\dfrac{2}{5}\):(1-\(\dfrac{1}{10}\))= -\(\dfrac{2}{5}\):\(\dfrac{9}{10}\)=-\(\dfrac{2}{5}\).\(\dfrac{10}{9}\)=-\(\dfrac{4}{9}\)

Câu 3

\(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}:\dfrac{5}{14}\)= \(\dfrac{7}{8}.\dfrac{4}{9}+\dfrac{1}{14}.\dfrac{14}{5}\)=\(\dfrac{7.4}{4.2.9}+\dfrac{1.14}{14.5}\)=\(\dfrac{7}{18}+\dfrac{1}{5}\)=\(\dfrac{35}{90}+\dfrac{18}{90}\)=\(\dfrac{53}{90}\)

Câu 4

\(\dfrac{2}{7}.\dfrac{3}{11}+\dfrac{2}{7}.\dfrac{8}{11}\)=\(\dfrac{2}{7}.\left(\dfrac{3}{11}+\dfrac{8}{11}\right)\)=\(\dfrac{2}{7}.1\)=\(\dfrac{2}{7}\)

Câu 11: A

Câu 12: C

Câu 13: B

Câu 14: A

Câu 15: B

Câu 10: Đúng

Câu 11: Cấm đi ngược chiều

Câu 14; Đúng

còn câu 4,12,13 nữa ạ.

16B

15B

13A

12D

11B

B

C

A

B

B

11.B

12.C

13.A

14.B

15.B

16.A

\(7-B\\ 8-A\\ 9-C.Tacó:n_M=n_{MCl}\\ \Rightarrow\dfrac{4,6}{M}=\dfrac{11,7}{M+35,5}\\ \Rightarrow M=23\left(Na\right)\\ 10-A.2NaOH+Cl_2\rightarrow NaCl+NaClO+H_2O\\ 11-D\\ 12-B\\ 13-B\\ 14-D.BTNT\left(S\right):n_{H_2SO_4}=n_{SO_3}=\dfrac{16}{80}=0,2\left(mol\right)\\ CM_{H_2SO_4}=\dfrac{0,2}{0,25}=0,8M\)

5 A

6 C

7 D

8 C

9 C

10 B

11 D

12 B

13 D

14 D

5 D

6 A

7 A

8 B

9 B

10 C

11 B

12 B

13 D

14 B

5 affected

6 time-consuming

7 precaution

8 making friends

9 for

10 therefore

11 dissolve

12 sewage

13 D

14 A

5C 6A 7A 8B 9C 10B 11A 12D 13D 14A

5. affected

6. time-consuming

7. precaution

8. making friends

9. for

10. therefore 

11. dissolve

12. sewage

13. Would you mind if I smoked ?

14. Really ? He's kind-hearted.