I. Prediction will

the tip of the iceberg

You can say something is the tip of the iceberg when it's just a small part of something much bigger.

under the weather

If you are under the weather, you're not feeling well.

2. In the end or at the end?(e.g. “However, in the end I decided to stick with my goldfish”, p. 39).
NB. When you use the expression "at the end", it needs the preposition "of". When you use "in the end", it doesn't need a preposition. There are also set expressions: to the end of time, to the bitter end.
1. We waited for nearly an hour and ____ the end we went without her.

a) at b) in c) on

2. The teacher set some homework ____ the end of the lesson.

a) at b) in c) on

3. There's an eraser ____ the end of my pencil.

a) at b) in c) on

4. My house is ____ the end of the street.

a) at b) by c) in d) on

5. We were exhausted ____ the end of the journey.

a) by b) in c) on

6. They get killed ____ the end of the film.

a) at b) in c) on

7. I'll love you ____ the end of time.

a) at b) by c) to d) on

8. They couldn't decide which one they liked and ____ the end they didn't bother.

a) at b) by c) in d) to e) on

9. They argue everything ____ the bitter end.

a) at b) by c) in d) on e) to

10. I paid the fees ____ the end of the course.

a) at b) in c) on

11. When do you get paid? — ____ the end of the month.

a) at b) on c) in

12. I couldn't decide what to get Ann for her birthday. ____ the end I didn't get her anything at all.

a) at b) in c) on

13. We waited ages for a taxi. We gave up ______ the end and walked home.

a) at b) on c) in

14. I'll be moving to a new address ____ the end of September.

a) in b) by c) at

15. Tom didn't want to lend us the money at first but ___the end he agreed.

a) at b) in c) to