24.　 Wear a hat to p_____ yourself from the sun..

23.　 Watch out for dangers such as spiders, snakes or _______(有毒的)plants.

22.　 Hiking is fun and exciting, but you shouldn’t forget _______ (安全).

21.　 The basic e_________　 you need for hiking is simple : good shoes, clothes and a backpack.

20.　 You will get close to nature and take _____(运动) at the same time.

19.　 Instead of spending your _____(假期)on a bus, in a hotel or sitting on the beach, you may want to try hiking.

18.　 Many of today’s travelers are looking for an unusual ______(经验) and adventure travel is becoming more and more popular.

17.　 They started to use English, but they also b ________ in　 some words from their own languages.

16.　 In 1776 America became an ______ (独立的) country.

15.　 In total, for more than 375 million people English is their mother t____.