厨房里发现了一只蟑螂，我赶紧拿了杀虫剂。

I quickly grabbed the insecticide when I spotted a ___cockroach in the kitchen.

网络谣言就像蟑螂一样难以彻底清除，即使被多次辟谣还是会不断出现。

Online rumors are like ___cockroaches - they keep coming back even after repeated debunking.