It wrenched us to say goodbye.
別れを告げるのはつらかった
It'd be a good idea to have some rest.
少し休むのがいいと思うよ
It'll be (a bit of) a push.
厳しい仕事になりそうだ
It'll bring him to his bearings.
それで彼は立場を悟るだろう
It'll cost you.
((略式))高くつくよ
It'll keep.
あとにしよう
It'll probably take, say, a thousand years to populate the solar system.
太陽系に人が住めるまで,まあ千年はかかるでしょう
It'll ruin my whole day.
お陰で1日丸つぶれだ
It's (been) ages [an age] since I saw you last.
ずいぶん長いこと会わなかったねえ
It's (all) Greek to me.
((略式))それは私にはちんぷんかんぷんだ