Sure, here are the corrected sentences with suitable prepositions or adverb particles filled in:

**GT12: Fill in each blank with a suitable preposition**

1. If she takes **up** the job of director, she will have to work harder.
2. The Government put **down** the rebellion with great severity.
3. There was a man giving **out** leaflets outside the church.
4. I can't make **out** the postmark on the letter, it looks like Basingstoke.
5. If he refuses to fall **in** with my plans, he can probably find someone more cooperative.
6. We walked on tiptoe **for** fear of being discovered.
7. Mary burst into **tears** when we told her about the accident.
8. I had to send **for** an electrician to mend the switch.
9. I was **about** to go when the telephone rang.
10. I'm relying **on** her to help me.

**GT13: Fill each gap in the following sentences with a suitable preposition or adverb particle**

1. I asked him to put **out** the lights if he was the last to leave the room.
2. The village has changed a lot thanks **to** the knowledge the children brought home.
3. The boys got **into** the garden by climbing up **over** the fence.
4. I turned **down** the job because it was badly paid.
5. My grandparents live **at** 34 Hai Ba Trung Road, in a flat **on** the top floor.
6. What do you buy these eggs **for**?
7. Look after the baby while I am **away**.
8. She wanted to know what aspect **of** learning English I found most difficult.
9. The children were amazed **at** the lion show at the circus.
10. Her small garden looks very beautiful in spring because all the flowers are **in** bloom.

**GT14: Fill each gap in the following sentences with a suitable preposition or adverb particle**

1. I received the news **with** a kind of naive enthusiasm.
2. He felt nervous before he started the first lecture of his life but he carried it **off** very well.