Some insects _____ the colour of their surroundings to protect themselves.

____ by taking part in practice can the young peoplebe toughened and hardened into steel

______ is a good form of exercise for both the old and the young.

My son seldom has breakfast.— It is unhealthy habit. You must ask him to change it.

We want someone to design the new art museum forus— ____ the young fellow outside have a try