单选题
In the jungle you may get hopelessly host within ten minutes after starting. That is (36) you should always carry a compass(指南针). In open country, during the day, you can (37) which way to go by studying the (38) At night, the stars are sure (39) to direction. In most places the jungle rooftop(顶)is so (40) that it is (41) to see the sun or the stars. (42) you must check your position by the (43) Keep careful. Watch the ground in front of you carefully. (44) and listen now and again. Avoid (45) , and rest often. In a place (46) is hot and damp, the person who walks fast will soon become (47) . A steady, show step is wisest in the long run. If you (48) your way, don't be scared(恐惧的) Try to (49) how long it has been (50) you were sure of your position. Make a mark (51) you are on a tree. Put the marks on (52) of the trees, so that you'll be able to see them from any (53) Then you can begin retracing your steps(顺序路返回), knowing that you can always find the place (54) which you started. (55) try to travel through the jungle at night except in an emergency (紧急情况)