1. France has taken the toughest stance with Iran in negotiations stretching back to 2003.

2. The new law is one of the toughest of its kind in the world.

3. Mr Musk described it as the toughest puzzle solved that the company has ever had to solve.

4. I order you to act in the toughest way, Putin said.

5. These are the toughest personal computers on the planet.

6. Mosul is the toughest job we have ever had.

7. Those job titles are among the toughest to fill in Silicon Valley, many corporate recruiters say.

8. In the sleep field, wearables may be the toughest sell.

9. He is the toughest person I know.

10. The toughest calls, they said, rise to an elite group of executives.

11. Titan makes the toughest paddles that I know of, Jones said.