5. Match each of the vessel below with a definition.

Ark, tug, lifeboat, houseboat, raft, rowing boat, powerboat, trawler, punt, launch, lightship, dinghy, ferry, paddle steamer, yacht, submarine, galleon, barge, canoe, liner

1. Kon-tiki was a famous one.

2. Some people like to make their home in one.

3. One might be transporting coal up or down the Rhine.

4. Noah would have had problems without one.

5. A small boat, often made of rubber.

6. Full of brave men who go out to sea in all sorts of weather to help other people.

7. A fishing boat that drags a net along the sea bed.

8. A participant perhaps in a sailing race or regatta.

9. A boat to carry people and their things from one point to another – and back.

10. Didn’t they use to travel down the Mississippi in one of these?

11. The Spanish Armada was composed of a number of these.

12. The QE2 is one.

13. An English form of gondola – propelled by a pole.

14. The river police might chase a suspect in one.

15. A Red Indian would have felt at home in one.

16. This one will take part in a very fast race.

17. You won’t get far without oars in this one.

18. A stationary vessel that will guide and direct others.

19. You won’t see it very often but it might see you through its periscope.

20. A little boat that will pull a much bigger one.

6. Modal verbs. Must and have to

Modal verbs express the speaker's attitude to the action indicated by the main verb.

Modal verbs are special verbs which behave very differently from normal verbs. Here are some important differences:

1. Modal verbs do not take "-s" in the third person. All modal verbs take the infinitive without the particle "to".

e.g. He can  speak Chinese.

She should be here by 9:00.

2. Their interrogative and negative forms are built up without the auxiliary do.

e.g. He should not be late.

You must not touch this thing.

Can you open this door?

Could you help me with this report, please?

There are two modal verbs to show obligation or necessity.  

Must strong obligation (possibly based on the speaker's opinion) The meaning of must is "The way I see/feel it in the present circumstances, it is necessary to.." (The speaker feels/admits/endorses the idea of obligation).

e.g. I must study today.

Have to strong obligation (possibly from outside). The same range of obligations when they are not felt personally. It is not an actual modal verb, but it is used like a modal. You must conjugate the verb "have" depending on the time and subject.

e.g. I have to work tomorrow.

She has to work tomorrow.

I had to work last night.

Must not and Don't have to

"Must not" and "don't have to" are completely different. "Must not" is a negative obligation and shows something that is prohibited. e.g. You must not eat in the computer room. (Food in the computer room is prohibited.) "Don't have to" shows something that is not necessary. A lack of obligation: it's equivalent Don't need to or Needn't. e.g. I don't have to work today.  (Working is not necessary.)

You don’t have to brush your hair every ten minutes, darling.