Darwin argued that as a coral reef grew up from a sinking island, it would become a fringing reef, then a barrier reef, and finally, with the disappearance of the island, an atoll.
an atoll好奇怪,是同位语吗?
不明白那里奇怪了,这和同位语有啥关系?
简单的序列动作而已,
1 first, it becomes a fringing reef
2 then, it becomes a barrier reef
3 finally, it becomes an atoll
with the disappearance of the island 只是个插入语。最后岛没了,成了环礁。