1. One expert believes the situation could be comparable to what occurred in the 16th century, when Europeans puzzled over how to classify the unfamiliar inhabitants of the Americas, and endlessly debated whether or not they were humans.
    有位专家相信，这一情形类似于16世纪时的一种情况，当时的欧洲人对如何对美洲的陌生居民进行归类感到困惑，并无休止地争论他们究竟是不是人类。

2. If the situation is unfamiliar, choose the answer closest to how you might react.
    如你不熟悉该情况，请选择最接近你可能作出的反应的答案。

3. From early youth he had cultivated it by memorizing verses in an unfamiliar tongue.
    从年轻时代起，他故意用一种人们不熟悉的外国语（例如希伯莱语），背诵它的诗篇，以锻炼自己的记忆力。