You should be candid with him about what happened.
何が起こったか，彼に包み隠さず話すべきだ
You should be straight with him.
彼に隠し事をすべきではない
You should do it immediately.
それをすぐになさってください（◆had betterより弱く丁寧）
You should feel mean for being so stingy.
そんなにけちけちして恥ずかしくないか
You should have been able to read the text over before the lecture.
講義の前にテキストをしっかり読んでおくことができたはずだ
You should have someone check that out.
人に確認してもらうべきだ
You should next take into account the color scheme.
次には配色を考慮しなくてはならない
You should really see the doctor before it's too late.
手遅れになる前に医者に見てもらうことを本気で忠告するよ
You should take a walk every day and, moreover, stop drinking.
毎日散歩してさらに酒もやめるべきです（◆andの強調）
You should take care not to catch cold.
風邪をひかないように
