所以我就想同大家分享一個實驗 。 呢個係一個 30 年前 ﹐ 幾個喺美國康州嘅牙醫 諗出嚟嘅實驗 。
So I wanted to share an experiment with you. This is an experiment that was conceived 30 years ago by a couple of dentists in Connecticut, United States.