on the eve of the election
選挙直前に
on the evening of March 31st
３月３１日の晩に
on the face of the document
書面に
on the faith of ...
…を信用して［保証として］
on the far [other, opposite] side of the room
部屋の向こう側に
on [((英))in] the firing line
第一線で；矢面に立って
on the first pass
最初の段階で
on [through] the grapevine
うわさで
on the grounds that ...
…という根拠に基づいて
(every hour) on the half-hour
毎正時３０分に（◇１：３０，２：３０など）
