1. (2019年天津卷)Their child is at the stage ________ she can say individual words but not full sentences.
解析：句意：他们的孩子正处于能说单个单词而不是完整句子的阶段。stage表示“阶段”，后接定语从句时，应该用关系副词where引导。
答案：where
2. (2019年北京卷) The students benefitting most from college are those ______ are totally engaged (参与) in academic life, taking full advantage of the college's chances and resources (资源).
解析：先行词为those，指大学生们，故用who引导定语从句，who在从句中作主语。关系代词that可以指人，填that也可以。
答案：who/that
