If all else fails, you can ask your father for help.
万事窮したらお父さんに助けを求めるといい
If anybody comes, tell them to wait.
だれかが来たら待つように言いなさい
if anything should happen to him
彼にもしものことがあったら
if (at all) possible
できたらI'll come, if (at all) possible.できたら行きます
If I could but talk to you for five minutes!
せめて５分間でもお話しできたら
If I had known your address, I would have written to you.
住所がわかっていたら手紙を書いたのですが
If I want to eat now, I'll eat, and that's all there is to it.
食べたくなったら食べる，それだけのことさ
if it were stored anywhere else
もしそれがどこか他の場所に保存されていたら
If it's heads, we'll go.
表が出たら行くことにしよう
if only
((略式))ただ…でさえあればよいが（◆帰結節が表現されないことがある）If only it would rain!雨が降ったらなあ
