单选题 Although we tend to think that they are basically the same animal, dolphins, porpoises, and fish are not alike. Despite how similar they might seem, these three animals ______ dolphins and porpoises are mammals while fish are not.
【正确答案】 C
【答案解析】[解析] 句意：虽然我们倾向于认为海豚、鲸、鱼类基本属于一种动物，但它们并不相同。尽管它们看起来很相似，但这三种动物还是有不同这处，海豚和鲸属于哺乳动物，而鱼类则不是。differ in在…不同。that引导宾语从句，所以C项正确。