英语时差：百分百干净（上）

Being clean is a good thing. After all, simply washing your hands regularly can help ward off flu and other contagious diseases. Is It Possible To Be Too Clean? Maybe… For the past few decades scientists have been debating the so called “hygiene hypothesis”–the idea that being exposed to a wide range of microbes early on helps strengthen the immune system. According to the hypothesis, too much anti microbial cleanliness at a young age can throw the immune system out of whack, causing it to overreact later on. Now, a study lends support to this idea. Scientists have found that bacteria living on our skin help prevent cuts from becoming inflamed when the immune system reacts to the wound.