Nonetheless, this female must incubate her eggs for three weeks 然而 雌雪雁必须花三周的时间孵蛋
less than three per cent of Antarctica is free of ice, 南极洲也只有不到3%的地方没有被冰封
three million bats leave the safety of the cave 300万只蝙蝠一起离开安全的洞穴
The East African Rift Valley holds three of the world's largest: 东非大裂谷内有着3个世界上最大的淡水湖
Lake Malawi, the smallest of the three, 马拉维湖是这3个湖泊中最小的
Its eyes do not fully open until three months after birth, 直到出生后的第3个月 它的眼睛才能完全睁开
She won't leave this cave for three weeks, 未来3周内 它都不会离开这个山洞
Three dogs close in on one impala. 3只野狗紧追一只黑班羚
Every year three million caribou migrate across the Arctic tundra. 每年 300万迁徙的北美驯鹿 都将穿越北极苔原