What can we learn about loneliness from the passage?

参考解析：

细节理解题。根据第四段第一句和第三句“Psychologists (心理学家) agree that one important factor in loneliness is a person’s social contact, e.g. friends, family members, co-workers, etc. For example, our families give us emotional support, our parents and teachers give us guidance, and our friends share similar interests and activities.”可知，孤独的人也有朋友，A项错误，心理学家一致认为，孤独感的一个重要因素是一个人的社会交往，B项正确；根据第三段第二句“Unlike the second type, chronic loneliness (慢性孤独) usually lasts more than two years and has no specific cause.”可知，与第二种类型不同，慢性孤独感通常持续两年以上，而且没有特定的原因，C项错误；根据第二段最后一句“Although this kind of loneliness can cause physical problem, such as headaches and sleeplessness, it usually does not last for more than a year.”可知，虽然这种孤独感可以导致身体问题，比如头痛和失眠，但通常不会持续一年以上。D项中的must太过绝对，故错误。故选B。