1. Your toothbrush 牙刷

The human mouth contains about 100 million microbes per milliliter of saliva. Those microbes eat the same food you do, and when you brush, food particles and bacteria stick to your toothbrush.
在人类的口中，每毫升唾液含有大约一亿个细菌。那些细菌和你吃同样的食物，当你刷牙时，食物残渣和细菌会粘在你的牙刷上。

Simple Fix 简单解决办法
After brushing, rinse your toothbrush with hot water and stand it up in a water glass to air-dry. Don't lay it on the counter, where it can gather other bathroom germs, and don't store it in a travel case, where bacteria can thrive in the moisture. You can even clean your toothbrush in the dishwasher once in a while.

刷完牙后，用热水清洗牙刷，并将刷头朝上放在水杯中风干。不要将牙刷放在浴室台面上，这样会吸收浴室里的其他细菌，也不要将牙刷放在旅行用的牙刷盒中，因为潮湿的环境容易滋生细菌。你甚至可以偶尔将牙刷放在洗碗机中清洁一下。