每日口說挑戰 為什麼人有不同血型？

今日挑戰句子

Lastly, if you hear the word "positive" at the end of your blood type, you have an additional antigen called the Rh factor. A universal blood donor has none of these antigens, which makes someone with O negative blood very valuable.

最後，當你聽到你血型後面有 "positive"(陽性的)這個字，代表你有額外的抗原，叫做叫做"RH"因子；一般的捐血者不會有這些抗原，這使陰性O型血型的人非常罕見。