我早餐喜欢吃面包和牛奶！因为它们很健康。
I like bread and milk for breakfast, because they are very healthy.
传统的观点认为类胡萝卜素之所以有意义，是因为它们很罕见：健康的雄性可以比它们的同类寻找到更多的色素。
The conventional view is that carotenoids are meaningful because they are rare: healthier males can forage for more of the pigments than can their inferior counterparts.
专家们认为这样的作用并不理想，因为存在已免疫的鸡携带与散播病毒的风险，虽然它们看上去很健康。
However, experts are divided over its usefulness, because there is the risk that vaccinated chickens might still harbour and shed the virus, while appearing to be healthy.
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