red flag

1 flag used as a symbol of danger, eg on roads, railways, etc （表示危险的）红色信号旗（如用於公路、 铁路等）. 2 symbol of revolution or communism （象徵革命或共产主义的）红旗.

rectum, recumbent, recuperate, recuperation, recuperative, recur, recurrence, recurrent, recurring, recurring decimal, recusant, recycle, red, red cabbage, red card, red carpet, red corpuscle (also red blood cell), Red Crescent, Red Cross, red ensign, red giant, Red Indian (Brit redskin), red lead, red light, red meat, red pepper, red setter, red tape, red wine, red-blooded, red-faced, red-handed, red-hot, red-letter, redbreast, redbrick, redcap, redcoat, redcurrant, redden,