NOTE (taken from the Hugon-Moore Ido Grammar); The word that is very often omitted in English, but should never be omitted in Ido; (1) The book I gave you (= the book that (or which) I gave you), La libro quan me donis a vu (in this case “that” is a pronoun: (2) I think he will come, (= I think that he will come); Me opinionas, ke il venos. (In this case “that” is a conjunction). It is generally omitted in English after verbs like to think, to hope, to wish, to believe. It is impossible to pay too much attention to this rule, as the correct use of the word ke is the key to a good international style for English-speaking students).

that is not easy - to ne esas facila.
to do that - facar to.
after that, he left - pos to (= pose) il departis.
that is to say (i.e.) - to esas (c.e.).
what is that? - quo esas to?
after that - pose.
some time after that - kelke pose.
besides that - ultre to.
(of that kind) tala.
that can (see suffix .iv).
that must be (see suffix .enda).
take that book - prenez ta libro.
the book that I gave you - la libro quan me donis a vu.
he spoke so that I believed him - lu parolis tale (= talamaniere) ke me kredis lu.
until that time - til ta tempo.
  • (conj.) ke;
(who which) qua; qui; quo;
instead of that he - vice ke il
so that - (in such a way that) tale ke.
in order that - por ke (with imperative).
I tell you now that you may be prepared - me dicas ol a vu nun, por ke vu esez preparita (= pronta).