1. a. Parents are usually worried about their children’s future.
    b. After the war I was very worried about the bomb.
  2. a. The captain was sure of his team’s victory.
    b. He is pretty sure of what the result is going to be.
  3. a. I tried out my uncle’s computer before I decided to buy one.
    b. They should have a system by which new ideas could be developed and tried out.
  4. a. In trying to solve problems, our responsibility is to do our best.
    b. In traveling abroad, you must be careful when you drink water.
  5. a. Our responsibility is to do our best and improve the solutions.
    b. They did their best to save their ship from sinking in the storm.