and that is today's lesson. 而这正是这节课的主题

143. She knows she needs to herd the prey into a tight group...
     雌虎鲸明白它需要将猎物驱赶到一起
144. ..but she can't do that on her own.
     但这项工作无法独自完成
145. It will take teamwork,
     而是需要团队合作
146. and that is today's lesson.
     而这正是这节课的主题
147. The young orca are quick to catch on.
     年轻的虎鲸理解的很快
148. The rays are surrounded.
     蝠鲼群被包围了
149. They dive...
     它们迅速下潜

来自《行星地球 第三季 第二集 Planet Earth S03E02 海洋》第 146 行