プログレッシブ和英中辞典(第4版)の解説
さいわい【幸い】
❶〔幸せ〕
折り返しお返事をいただければ幸いです
「I hope that you will be able to [It would be very helpful if you could] give me a prompt reply.
お役に立てば幸いです
I'll be glad [happy] if I can be of (some) service to you.
❷〔都合のよいこと〕
幸い（に）けが人はなかった
Fortunately no one was injured.
私が訪ねたとき幸い彼は在宅だった
Luckily he was at home when I called on him.
幸い（に）彼に会うことができた
I had the good fortune to meet [see] him.
彼が動揺したのを幸いにスマッシュを決めた
Taking advantage of his confusion, I smashed the ball past him for a point.
天候が幸いして美しい富士山を眺めることができた
Favored [Blessed] with good weather, we had a lovely view of Mt. Fuji.
世の中は何が幸いするか分からない
In this world you never know what may 「turn out to your advantage [prove to be helpful].