- the most visible signs of life on our planet.
植物 是我们星球上的生命最鲜明的标志 - Back in Earth's distant past,
在地球遥远的过去 - the arrival of plants
植物的到来 - created new habitats for the next invaders from the sea.
为来自海洋的下一批入侵者 创造了新的栖息地 - The first animals to ever set foot on land were the arthropods.
率先踏上陆地的动物是节肢动物 - Relatives of the trilobites,
它们是三叶虫的亲戚 - their hard exoskeletons had served as useful armor underwater.
坚硬的外骨骼在水下是有用的护甲