大家还记得芹菜事件的教训么？80年代中期，美国的芹菜培植者曾推崇过一种他们认为非常好的新品种，不仅抗虫性强，而且可以使产量显著提高。但是有一个小问题，触弄过此芹菜梗的人不久就开始为发生严重皮疹而抱怨。皮肤病学家发现，这种芹菜会不断分泌出扫若仑（psoralen），? Do you still remember the lesson of celery? In the mid-1980s, celery growers in the United States had respected a new breed they considered to be very good, not only resistant to insects but also markedly increased yields. However, there was a small problem. Those who touched the celery stem soon began complaining about a serious rash. Dermatologists find that this celery will continue to secrete psoralen ,?