2. couldn't
3. could
4. were
5. could
6. weren't
7. were
8.could
9.were
1 - if we keep on using more and more cars, we will run out of oil.
2 - if we run out of oil, we will need other kinds of energy.
3 - Pollution will increase if we use more oil and coal.
4 - if pollution increases, more and more tress will die.
5 - the climate will change if more trees die.
6 - if we try to control the pollution, it will be very expensive.
7 - if we don't control pollution soon, it will be too late.
Has your sister many friends?No,she hasn't.
Are cups green? No,there aren't green,they are blue.
Has your friend blue car?No,his car is yellow.
Are book interesting?No,they aren't.
2. this
3. those
4. this
5. this
6. these
7. that
8. that
вроде так