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 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 wait until you see him next.
次回彼に会うまで待てば
You shouldn't have come here to begin with.
そもそもここへ来てはいけなかったのです
You will always find a good friend in me.
いつでも力になってあげます
You will doubtless succeed, but you still have to be cautious.
おそらくうまくいくとは思いますが，やはり慎重を要するでしょう
You would be well advised to do so.
そうしたほうがいいですよ
You'd better leave now, or else you'll miss your plane.
もう出発しなさい，でないと飛行機に乗り遅れますよ
You'll be made very welcome.
きっと大歓迎されるでしょう
