誕生日に on someone's birthday

誕生日に,これらの花を私の母に贈ってください Please send these flowers to my mother for her birthday.

誕生日に~をあげる〔人の〕 give someone ~ for his birthday

誕生日に~をプレゼントする〔人の〕 give someone ~ for his birthday

誕生日にお金をもらえたらデジカメを買いたい If I get money for my birthday, I want to buy a digital camera.〔話者にとって現実となる可能性が高いのでif節の動詞は、過去形（仮定法過去）ではなくて、現在形でよい。〕

誕生日にそのレストランに行くと,飲み物がただになるよ If you go to that restaurant on your birthday, you get a drink on the house.

誕生日にとても高価な贈り物をする〔人の〕 give someone an extravagant gift for his birthday

誕生日にもらったもの〔人が〕 what someone received for his birthday

誕生日にガールフレンドが買ってくれた時計は,僕にぴったりだ The watch my girlfriend bought me for my birthday fits me like a glove.

誕生日にバラを送ってくれるなんて,あなたは思いやりがあるのね It was thoughtful of you to send those roses on my birthday.

誕生日に何をあげればいいのか分からない〔人の〕 have no idea what to get someone for his birthday

誕生日に何をもらいましたか What did you get for your birthday?

誕生日に何をプレゼントすればいいのか分からない〔人の〕 have no idea what to get someone for his birthday

誕生日に何を欲しがっているのか見当が付かない〔人が〕 have no idea what someone wants for his birthday

誕生日に歌を歌う〔人の〕 sing a song on someone's birthday

誕生日に花束を送る〔人の〕 send someone flowers for his birthday

誕生日に絵をプレゼントする〔人の〕 give a painting to someone on his birthday

誕生日に残業する work late on one's birthday

誕生日に植樹する plant a tree on one's birthday

誕生日に贈ってくれた花〔人が〕 flowers someone sent one for one's birthday

誕生日に着る礼服〔国王が〕 birthday suit

誕生日に必ずプレゼントをする〔人の〕 always remember someone's birthday

誕生日に必ず電話をかける〔人の〕 be sure to call up someone on his birthday