The best way to explore _______ countryside is on _______foot.
17. Be when you cross the road.
16. You cannot be too careful. Which of the following sentences doesn’t have the same meaning of the underlined sentence? _____
15. In an emergency, you should remain _____.
14. It was a _____ evening and I really had a good sleep.
13. The foreman(工头) beat him _____ , and the other workers were very angry with him.