every day 本身是名词,既可以作主语也可以作宾语,不过表示时间以及方式、处所、距离、度量的名词常可以转化为副词,直接用作状语.
另如：
(Last night) was unpeaceful. 昨晚很不平静l.【主语】,
My brother called me from Shanghai (last night). 我的兄弟昨晚从上海打电话给我.【时间状语】
Eight kilometers is roughly equivalent to (five miles). 八公里约等于五英里.【介词宾语】
John can walk (five miles) an hour.约翰一小时能步行五英里.【程度状语】
Only in (this way) can the critical mass of participation be reached.只有这样才能凑足参与人数.【介词宾语】
Come(this way),please.请这边走.【方式状语】
They actually moved down from (upstairs) because the rent's that expensive.他们确实从楼上搬到了楼下,因为房租太贵了.【介词宾语】
You don't have to go running (upstairs) every time she rings. 用不着她一来电话你就往楼上跑.【处所状语】