s. difficult to analyze or understand
a. 复杂的
[医] 并发的
1. The instructions for assembling the furniture are very complicated.
组装家具的说明书非常复杂。
2. She has a complicated relationship with her coworkers.
她与同事的关系很复杂。
3. Learning a new language can be complicated, but it's worth it.
学习一门新语言可能很复杂，但这是值得的。