I need to get to Lyons by nightfall.我必须在夜幕降临前到达里昂。

It seemed, by nightfall, as if everything was coming together.似乎所有的事都会在夜幕降临前一起到来。

By nightfall the farmhouse had been razed to the ground.农舍在夜幕降临前已被夷为平地。