North American diving duck with a grey-and-black body and reddish-brown head
black-and-white North American woodpecker having a red head and neck
双语例句
Scientists do not fully understand how anesthesia works, but the findings offers clues, as people with red hair have a certain genetic variant. 科学家们还不完全了解麻醉剂的作用机理，而这一发现为此提供了线索，因为红头发的人具有一种特定的遗传性变型。
