That's a side issue.
それは副次的な問題にすぎない
That's a sure recipe for failure.
そんなの失敗にきまってる
That's a sure thing.
きっとうまくいく
That's a switch!
((米略式))そいつは珍しい
That's [It's, What] a terrible thing to say!
なんてひどいことを言うの
That's a thought!
((略式))それはいい考えだ
That's a tough question [problem].
難しい問題だ
That's a turnup for the book(s).
((英略式))それは驚くべきことだ
That's an idea!
((略式))それも一つの考えだ
(But) that's another story.
((略式))（だが）それは（まったく）別の話だ
