Complete the sentences with one of the idioms in the correct form:

1. keep a secret,
2. keep a straight face,
3. put in time,
4. put on an act,
5. put right,
6. keep in touch,
7. keep one's chin up,
8. put the cart before the horse,
9. keep one's word,
10 keep one's head

It was difficult to _____________________________ when the man fell off his chair into the grass.