1. (imp.) of Shall.

2. (imp.) Used as an auxiliary verb, to express a conditional or contingent act or state, or as a supposition of an actual fact; also, to express moral obligation (see Shall); e. g.: they should have come last week; if I should go; I should think you could go.

be expedient be forced be in for be necessary be obliged cannot do otherwise cannot help but had best had better have got to have need to have to must need need to needs must ought ought to