parasitic hypothesis

例句：

1. 1. Parasites can cause serious health problems for their hosts.
   寄生虫可以给宿主带来严重的健康问题。
2. 2.The parasitic plant is a common sight in many tropical rainforests.
   寄生植物是热带雨林中常见的景象。
3. 3.Parasitic diseases are often difficult to treat due to the host's immune system's resistance.
   由于宿主免疫系统的抵抗力，寄生疾病往往难以治疗。