单项选择题
During a trio to observe wild animals in Africa I encountered the least brave animal on earth the wildebeest(角马).I sat on a riverbank for three hours watching a group of thousands build 【A1】the courage to drink water.
More than a million wildebeests 【A2】 northward into the wetlands. It is a long.dry and difficult.journey. Frequently, the only available water is the Grumeti River, 【A3】 represents both life and death.Unlike some creatures that can take moisture 【A4】 the grass they eat, wildebeests must drink from the river to live.The river supports other wildlife. including 【A5】 that kill and eat other animals.Though thirsty 【A6】 traveling, the wildebeests stand back from the water, sensing possible danger.
Moving slowly toward the bank can 【A7】 hours, as an individual wildebeest steps forward.steps back and then carefully steps forward again. More wildebeests gat her together and advance,gradually pushing the leaders to the river, 【A8】they want to go or not. It's been a long time 【A9】 they drink last time, and you feel their anxiety for water.
Lions are possibly on the 【A10】, saving energy as they wait for an opportunity for lunch. Once.the large group moves to the river. lions could 【A11】. making the group running in a wild and.uncontrolled 【A12】 The mad rush would raise a dust cloud that blocks the 【A13】 of the wildebeests. nearby. A kill is almost guaranteed.
Sitting on that riverbank, I noticed that a young wildebeest finally stepped ahead and drank.while the 【A14】 adults held back. Soon others began drinking. But 【A15】 lining up along the bank.taking turns, they gathered and pushed. Some had to walk farther into the water than they were 【A16】to go. Those pushed farther in water got frightened and in 【A17】 frightened the others. They all.retreated hastily and returned to their route. Only the few that were 【A18】 enough got a drink The.others went 【A19】. There was no danger that day. Only the wildebeests' fear and 【A20】 of courage kept them from drinking.
【A19】