・I regret [am sorry] that he should be (＝is) so weak. 彼があんなに弱いのは気の毒だ.

・It is strange that you should not (＝don't) know it. 君がそれを知らないとは不思議だ.

・I wonder that such a man as he should commit an error. 《英》 あんな男が失策をしたのかなあ.

・It is natural that he should have refused (＝(has) refused) our request. 彼が我々の要求を拒んだのは当然だ.

・It is not necessary that I (should) be there. 私がそこへ行く必要はない.

・It is surprising that he should have been (＝has been, was) so foolish. 彼があんなにまぬけであったとは驚きだ.