红灯用英语red lampred lightWhen injected behind the retina at the back of the eye, the gene produces a protein that is sensitive to red light. 当这种基因被注射到位于眼睛后部的视网膜后面时,会生成一种能感应红色光的蛋白质。
showing redsharp warning of a red lighthave red light on give sb a red lightflash red以上的说法都可以,具体看你用在怎样的句式里。用比喻义的时候,比如健康亮起了红灯什么的,也可以用 have serious problems 之类的~