когда ставиться предлог after

РЕБЯЯЯТОЧКИ И ДЕВЧООНОЧКИ ПОМОГИТЕ!!!!! ВСЕО ЛИШЬ 8 ПРЕДЛОЖЕНИЙ!

4 Emily and her friends have come to visit Jane. The hospital is holding a conference on healthy lifestyles. A government health advisor, Debora Bulmer, Doctor Bernard Foam and John Small, a fitness coach, are taking part. Read the following statements. Which of them do you agree / disagree with?'

Model:I think it's true that everybody should do exercise three times a week.

8.    "Twenty years ago American children didn't spend so much time in front of the TV."
9.    "Physical activity is good for your health."
10.    "The government should spend money on new sports clubs for children."
11.    "Teenagers should eat at least four pieces of fruit and four servings of vegetables every day."
12.    "Eating a lot of meat is good for you."
13.    "We must do our best to tell children about a balanced diet and open free sports clubs."
14.    "When I was a child, we didn't have convenience food."
15.    "Swimming and jogging burn a lot of calories."
16.    "You lose weight if you burn fewer calories than you take in."

РЕШИТЬ УРОВНЕНИЕ:

1)2X+(X-3)-23-(2-3X)=0

2)4+x-8+(2x-5)=0

2x+17=22+3x

18+3x=x+14

25-4x=12-5x

13x+27=16x+4.5

21x+45=17+14x

13x+70=2x+15

 прошу очень нужно помогите

ширина реки 20м., средняя глубина 1,5 м., скорость течения 2м / с. Определите расход воды в реке на этом участке.