昨天玛丽在家的英语表达可以是 "Mary was at home yesterday." 来源方面，这是一个常见的英语结构，用于描述某人在某个特定时间做某事。
一些例句及其中文翻译：
"John was at work yesterday." (约翰昨天在工作。)
"Sara was at the pbrary last night." (莎拉昨晚在图书馆。)
"They were at the park the day before yesterday." (前天他们在公园。)
总的来说，在英语中，通过在句子中插入一个表示时间的状语，可以很容易地描述某人在某个时间做某事。