three quarters of the forest _ cvered with trees of broad leaves while the rest_ pine trees 填be动
问题描述：
three quarters of the forest _ cvered with trees of broad leaves while the rest_ pine trees 填be动
说明原因
答
three quarters of the forest( is )covered with trees of broad leaves while the rest(is)pine trees .
整句话的意思：森林的四分之三是阔叶林（,剩下的（四分之一）是松树林.
这里主语是forest（森林）,因此用单数.也就是说把森林看作是一个整体,分成两部分,一部分是阔叶林（单数）,一部分是松树林（单数）.