1. D
Fall through: not to be completed, not happen (plan, idea, arrangement)
2. A
Few and far between (idiom): not frequent, scarce
3. B
Die down: become less strong, loud, etc
4. C
Come down with: Get an illness (not very serious)
Fill in for: do one's job when they are away
5. B
For the time being: meanwhile
6. D
Hold on to: hold sth tightly in order not to drop it
7. A
Part with sth: give away, get rid of sth
8.C
Out of order: not working correctly
9.A
Cash in hand: (n) Existing money, payment made directly in cash, rather than through a bank
10. C
Next to nothing: almost
11. B
Be on pins and needles: to be nervously waiting for sth that is going to happen
12. C
Be on the tip of one's tongue: about to come to mind
13. A
make sense of sth: understand sth
14. D
On the whole: in general
15. D
Hit it off = get on well