Underling the correct word in each sentence 1)where's an/the electric heater? i can't find it 2)what happened at an/the end of a /the film? 3)david has an/the appointment at a/the opticians 4)an/the old person sometimes feels lonely 5)peter built a/the largest model plane in a/the world 6)luckily a/the fire brigade soon came and put out a/the fire 7)harry's mother bought him a/the guitar for his birthday present 8)i'm thinking of buying a/the new pair of trouser 9)in the end there was a/the war between the two countries 10)i didn't know an/the answer to a/the question ,so i left it out

1) Where's the electric heater? I can't find it.
2) What happened at the end of the film?
3) David has an appointment at the opticians.
4) An old person sometimes feels lonely.
5) Peter built the largest model plane in the world.
6) Luckily the fire brigade soon came and put out the fire.
7) Harry's mother bought him the guitar for his birthday present.
8) I'm thinking of buying a new pair of trousers. 
9) In the end there was a war between the two countries.
10) I didn't know the answer to the question, so I left it out.