complex diseases的用法和样例：
例句
- Myocarditis is a complex disease because multiple pathogenetic factors play a role.
摘要心肌炎是一种由多种致病因素所引起的复杂疾病。 - However, he said, understanding the molecular nature of this single genetic defect, which is at the root of a familial form of such a complex disease, offers invaluable clues.
然而，他又说，理解单个遗传缺陷的分子本质，其是如此复杂疾病的一种家族性形式的根源，提供了无价的线索。
