i was at the office on monday

i was at the office on monday
i was at the office on monday
i was at church on sunday
这两句很没意思
如果要定指在这个 office 或 church 又该怎么表达?

如果表示特指,那么特定修饰语（定冠词“the”或者指示代词 或者物主代词）是一定要加的
如 I am at my office/this office/the office which is in Shanghai.
同理 特指church时 和 office用法一样
注：只是church还可以表示泛指,即“我在教堂”（并不指明在哪一个）
于是用at church 等同于 at hospital/school/home 等等...