复杂的事物；使某物难以理解之处，令问题难以解答（或解决）的方面
the features of something that make it difficult to understand or find an answer to
There are a lot of complexities surrounding this issue. 此事牵涉到许多错综复杂的情况。
Doctors spend their whole lives trying to understand the complexities of the body's systems.
These resources have been developed to help students understand the complexities of foreign policy.
The legacy of empire undoubtedly produces moral complexities.
The complexities of this situation mean there's no simple solution for moving forward.
The film engages with many of the historical complexities of the battle.
See also: complexity