课文填空。 根据课文原文,填入所缺内容. ★ It was not immediately obvious that water was 1 the development of life. ★ This produced 2 , which made it possible for life to develop. ★ I earned my passage by working as an unpaid hand, which 3 . ★ When they crossed the Rocky mountain, they 4 some mountain goats and even a grizzly and an eagle. ★ Many of them 5 riding wild horses and can win thousands of dollars.