Woodsmen, hunters and trackers learned to follow and read the (21) left, behind (22) animals, men, nature and time. Their ability to survive (23) on their skills in (24) these signs. Soon they reasoned that if signs left behind accidentally had (25) , they could leave signs deliberately(故意) for their (26) future use or for the benefit of (27) following them. (28) trail signs and symbols (29) and soon became (30) standardized. A hunter in a forest backed(砍) pieces of back(树皮) off some of the trees in his path so that he could find his way back (31) so that others could (32) him.

32（）

题库:英语 类型:最佳选择题 时间:2017-07-03 02:49:39 免费下载:《单选集》Word试卷

Woodsmen, hunters and trackers learned to follow and read the (21) left, behind (22) animals, men, nature and time. Their ability to survive (23) on their skills in (24) these signs. Soon they reasoned that if signs left behind accidentally had (25) , they could leave signs deliberately(故意) for their (26) future use or for the benefit of (27) following them. (28) trail signs and symbols (29) and soon became (30) standardized. A hunter in a forest backed(砍) pieces of back(树皮) off some of the trees in his path so that he could find his way back (31) so that others could (32) him.

本题关键词:R-R间期,R-R间距,荠r,R波,r麻根,r麻花,r麻皮,r麻叶,石荠r,S-O-R;