5 Change each sentence into the negative and interrogative form.
1 We shall catch a bus to the railway station.
2 Yesterday evening the doorman at the hotel took our suitcases
and pointed the way to the desk-clerk.
3 Her friends will take a taxi to the airport in twenty minutes.
4 Mark often travelled on business last year.
5 They have just arrived.
6 We had a pleasant and enjoyable voyage on the Black Sea
last summer
7 She has been to Spain already.​

Some people say that damage to the environment is the biggest problem facing the world. However, other people say that there are other problems that are more important.

Some people think that environmental problems are the most dangerous whereas others don’t agree.

I think that nowadays environmental catastrophe is the biggest threat. First of all, global worming can bring us a lot of troubles. If the ice melts, a lot of countries will be flooded. Second, Ozone holes can cause the death of a lot of lands. Also bad food, air and water can be the reason of various diseases.

At the same time there are people who say that overpopulation, lack of food and nuclear war can be even more dangerous.

In my opinion these people have a point. These threats can kill our planet too. Nevertheless, they are easier to control than environmental problems. Nuclear moratorium, new technologies allow us to solve these problems.

In conclusion I'd like to say that if we weigh all the facts that say that danger to the environment is the biggest problem against the ones that support other threats, we'll see that the facts that support the statement outweigh those against.