should (third-person singular simple present should, no present participle, no simple past or past participle) (modal, auxiliary, defective) Ought to; indicating opinion, advice, or instruction, …

「should we」の意味・翻訳・日本語 - した方がいいですか｜Weblio英和・和英辞書

Like other similarly formed contractions, speakers only use should've to replace the modal sense of should have, i.e. where have precedes a past participle: You should 've gone.

(euphemistic, preceded by "a") Used to denote that the speaker is referring to a specific person or thing that they do not want to name directly, implying that the listener should infer the identity …

「shouldn't」の意味・翻訳・日本語 - should not の短縮形｜Weblio英和・和英辞書

「Should Know」の意味・翻訳・日本語 - 知っているはず｜Weblio英和・和英辞書

Transl, page 169: The armies drawing constantly nearer to each other, the king advised with his council, whether he should march against the Britons, or sall upon the count of Gharolois.

Were we to take a portion of the skin, and contemplate its exquisite sensibility, so finely appropriated […] we should have no occasion to draw our argument, for the twentieth time, …

Assuming that it is true, what should we do about it? それが 本当だ と したら, そのこと について どうしたらいいの だろう (cf. assume 2b).

「should have」の意味・翻訳・日本語 - すればよかった；よかったのに；べきだった｜Weblio英和・和英辞書