What complicates the issue is the burden of history.是历史包袱使该问题复杂化。

Bad weather continues to complicate efforts to deal with oil spilling from the tanker.持续恶劣的天气使得处理油船漏油的工作复杂化了。

To complicate matters further, everybody's vitamin requirements vary.更麻烦的是, 每个人的维生素需求量是不同的。