第27题: [填空题]The paleontologists were puzzled by the fact that the early mammals had high-crowned teeth be cause the grasses at that time were ______. 参考答案:rare 答案解析:阅读题干可以发现这是有关牙齿的内容,所以定位在第二个小标题下。通过阅读发现这一标题下的第六段有it was thought queer for grasses were still quite rar