1/ His teacher regrets _______ him that his application for the job has been turned down.

           A. tell             B. to tell                     C. telling                    D. tells

2/ The workers stopped _______ a rest because they felt tired.

           A. take B. to take                   C. taking                    D. took

3. At school, students usually take part in_______money for charity.

A. raised                B. to raise                     C. raising               D. raise

4.  Let's__________for a walk.

A. go                       B. to go                            C. going                  D. went

5. Why don't you consider to visit me? I really look forward to_______you.

A. see                     B. seen                   C. seeing                D. saw

6.  It's impolite___________people about their salary.

A. asked                B. to ask                      C. ask                     D. asking

7.  Don't_________in class.

A. talking              B. to talk                       C. talked                D. talk

8. Students are always interested in____________ a party.

A. to have              B. have                       C. having               D. had

9.___________the exams, students have to learn hard.

A. To pass             B. Passed                       C. Pass                   D. Passing

10. Would you please show me _________ yahoo messenger?

a. to use                     b. using                      c. how can I use          d. how to use

11. Mary told me _________ to go to the bank

a. don’t forget             b. not forget                c. not to forget d. should not forget

14. Let him _________ it himself

a. do                          b. to do           c. does                       d. doing

15. School children are looking forward to _________ on holiday

a. go                          b. be going                 c. going                      d. went

16. 

Mr. Minh _________ wearing a crash helmet when he goes somewhere on his motorbike

a. used to                    b. is used to                c. is using                   d. used

a) \(CuO+2HCl\rightarrow CuCl_2+H_2O\)

b) \(n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\)

Theo PTHH: \(n_{CuCl_2}=n_{CuO}=0,05\left(mol\right)\Rightarrow m_{CuCl_2}=0,05.135=6,75\left(g\right)\)

c) m_{dd sau pư} = 156 + 4 = 160 (g)

\(C\%_{CuCl_2}=\dfrac{6,75}{160}.100\%=4,21875\%\)

a, \(A=\dfrac{1}{7}.6+\dfrac{1}{7}.\dfrac{2}{7}+\dfrac{1}{7}.\dfrac{5}{7}=\dfrac{1}{7}\left(6+\dfrac{2}{7}+\dfrac{5}{7}\right)=1\)

b, \(A=\dfrac{4}{3}.\dfrac{13}{9}-\dfrac{4}{3}.\dfrac{40}{9}=\dfrac{4}{3}\left(\dfrac{13}{9}-\dfrac{40}{9}\right)=-4\)

c, \(A=\dfrac{5}{7}\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}.\dfrac{-7}{11}=-\dfrac{5}{11}\)

`A=6/7+[1/7(2/7+5/7)]`

`A=6/7+(1/7*1)`

`A=6/7+1/7`

`A=1`

~~~~~~~~~~~~~~~~~~~

`A=4/3*13/9-4/3*40/9`

`A=4/3(13/9-40/9)`

`A=4/3*(-3)`

`A=-4`

~~~~~~~~~~~~~~~~~~~

`A=5/7(5/11+2/11-14/11)`

`A=5/7(-7/11)`

`A=-5/11`

`A=6/7 + 1/7 . 2/7 + 1/7 . 5/7`

`A = 1/7 . 6 + 1/7 . 2/7 + 1/7 . 5/7`

`A = 1/7 . ( 6 + 2/7 + 5/7)`

`A=1/7 . ( 42/7 + 2/7 + 5/7)`

`A=1/7 . 7`

`A=1`

________________________

`A=4/9 . 13/3 - 4/3 . 40/9`

`A=(4.13)/(9.3) - (4.40)/(3.9)`

`A=(4.13-4.40)/(9.3)`

`A=(4.(13-40))/27`

`A=(4.(-27))/27`

`A=-4`

___________________________

`A = 5/7 . 5/11 + 5/7 . 2/11 - 5/7 . 14/11`

`A  =5/7 . ( 5/11 + 2/11 - 14/11)`

`A=5/7 . ((5+2-14)/11)`

`A=5/7 . (-7)/11`

`A=(5xx(-7))/(7xx11)`

`A=(-35)/77`

`A=(-5)/11`

Bạn tham khảo cách làm:

https://hoidap247.com/cau-hoi/179838

\(2x^2-9x+9-2\left(x^2-2x-35\right)=8\)

\(\Leftrightarrow-5x+79=8\Leftrightarrow x=\dfrac{71}{5}\)

`(2x-3)(x-3) - 2(x+5)(x-7)=8`

`2x^2 -9x+9 - 2x^2 -4x - 70 = 8`

`-5x + 79 = 8`

`-5x = -71`

`x=-71 : (-5)`

`x=71/5