bảo toàn điện tích ta có: 0,1*2+0,1=x+y =0,3

lại có 30,9= 0,1*137+0,1*39+35,5*x+62*y

giải hệ x,y ta có : x=0,2; y=0,1

x=0,2

y=0,1

1.has being taught / graduated

2.reported/captured

3.thanked

4.stole

5.had lived/broke

6.am ( usually)

7.has driven/knew

8.speak

9.will wag/sees

10.will leave/knows

1. he is thought to have stolen my car.

2.he is said to have been a good doctor.

3. 13 was believed to be an unlucky number.

4.the man was rumored to be still living.

5.she was declared to win the competition.

6. she is declared to have won the competition.

7.English is known to be an international language.

8.Jack London's life and writting are thought to represent the American love of adventer.

9.he was said to be the brightest sudent in the class.

10. he is said to have been the brightest sudent in the class.

11. he is thought to have died a natural death.

how does she sing?

what does she do at your school library?

1.this machine must not be used after 5.30p.m

2.the chalk board is always erasered by one of the students

3.some of my books have been taken away

milk is used for making butter and cheese

the room was filled with smoke

how many game was played by the team?

the lessons are being written by the students now

this house was built 100 years ago

this 2 job have to be done at once

is big cakes being made for party