237 (_o_). "Should" and "would" follow the rules of "shall" and "will" when employed in parallel circumstances. They express:--
(1). Supposition, or a future that is doubtful, conditional, or merely supposed (par. 192), as "_I should do it if I knew how._"
(2). Duty or obligation (par. 237 (_a_)) as "He _should_ not do that."
(3). Determination, as "Nothing could influence him, he _would_ do it."
(4). The softening of an expression (par. 194), as "Would you object to do that?"
(5). The future in _indirect_ speech (par. 232), as "_She said she would (will) come._"
(6). Would, when it signifies _custom_ or _habit_, is sometimes translated by adding the suffix _-AD-_ to the verb.
The following sentences will show how these various meanings may be expressed in Esperanto. The number before each example shows under which class of meanings it comes.
Examples.--(1). _Mi ĝin farus, se vi min permesus_ = I should do it if you would permit me. (1). _Li min frapus, se li ne timus_ = He would strike me if he were not afraid. (3). _Li insistis ĝin fari malgraŭ la danĝero_ = He _would_ do it in spite of the danger. (4). _Ĉu vi donus al mi tiun libron?_ = Would you give me that book? (1). _Se vi vidus Johanon morgaŭ_ (2) _vi devus diri al li, ke li ne aĉetu tiun domon_ = If you should see John to-morrow, you should tell him not to buy that house. (5). _Ŝi diris al mi, ke ŝi venos_ = She told me that she would (will) come. (1). _Mi iomete suspektis, ke ili venos_ = I had a slight suspicion that they would come. (6). _Ili ofte rajdadis tra la arbaroj, kie la branĉoj tuŝadis iliajn ŝultrojn, kaj la birdoj kantadis inter la freŝaj folioj_ = They would often ride through the woods, where the branches would touch their shoulders, and the birds would sing amid the fresh leaves.
237 (_p_). "Must" and "Have to" always signify physical or moral obligation, and are stronger terms than "ought," which implies moral obligation or duty. Compare "_You must_ (_have to_, _are to_) _go_" with "_You ought to go._" The former can be rendered by devi, and the latter, "ought," by _deci_, or some word implying moral obligation. Devi is also used for "ought" in the Conditional mood; devus, in this case, being the softened form of the Conditional mood (see par. 194). Care must be taken not to translate "must" when it signifies "have to" or "am to" by havi or esti (see par. 237 (_a_) on devi).