跳蚤寄生在猫身上会导致宿主皮肤刺激。

The ___parasitism of fleas on cats can lead to skin irritation for the host.

他长期依赖朋友的经济援助却从不回报，这种行为就是典型的寄生。

His long-term reliance on friends' financial help without ever giving back is a clear example of ___parasitism.