When we., the sun.

1.a garbage is not only ugly, bute dangerous because it causes an air pollution.

2. cars are an important part of a life for most people. but cars also cause a pollution and release fume.

3. in canada people don't realise that they throw out 10,000 tons of a waste.

4. over 14 billion pounds of a waste per year is throw out to sea and it kills millions of sea animals.

5. if we want to breathe  a healthy air we have to think about what we do.

6. because of our lack of a knowledge there is now a huge hole over an antractic.

7.a water is a vital element of a life.

every week

если имеется в виду, что надо дать какой-то показатель, который будет указывать на то, что это настоящее простое время используется works

1)she wasn't invited to the party by them.

2)the windows were not left open by me.

  3) the light wasn't turnud off by them.

  4)some friends have been invited to tea by me.

  5) an english book has been given me by her.

  6)have the letter been written yet?

  7) we have been told a lot of interesting things by them.

to be afraid, to be tired, to be upset, to be hungry, to be successful, to be busy, to thirsty, to be scared, to be lucky, to be worred 

to think, to go, to sleep, to stay, to run, to want, to get, to sit, to keep, to see