==========complex 暗示很多相关联部分的组合：
The composer transformed a simple folk tune into a complex set of variations。这位作曲家把一首简单的民歌小调改编成一首复杂的变奏曲。
a complex carbohydrate 碳水化合物

==========complicatedd 强调各部分之间的细微关系：
Middle Eastern politics is so complicated that even experts cannot agree on a cohesive policy.中东政治如此复杂以致于甚至专家们也难以制定出统一的政策。
a complicated piece of machinery 一件复杂的机械


===========intricate 着重于各部分交织在一起很难区分或分析：
It's a novel with an intricate plot. 这是一部情节错综复杂的小说。
No one could soar into a more intricate labyrinth of refined phraseology. 没有人能够攀进复杂的专业术语的优雅迷宫