This is it. 这就是了

99. Not only is their prey seasonal, it's also hard to find.
    不仅它们的猎物是季节性的,而且很难找到
100. They've been searching for days without a sign.
     这些狼虽觅食多日 但一无所获
101. Somewhere in this immense landscape there is food for them.
     在这无边无际的大地上的某处 有它们所需要的食物
102. This is it.
     这就是了
103. Caribou.
     北美驯鹿
104. Travelling 30 miles a day,
     驯鹿日行30英里
105. they can cover nearly 2,000 miles during the summer months.
     差不多整个夏季能够行进2000英里

来自《行星地球 第一季 第七集 Planet Earth S01E07 伟大草原》第 102 行