Modern Spanish Grammar: A Practical Guide

EXPRESSING SUPPOSITION 50.150.1.4 Deber (de) + estar + gerundThis construction expresses supposition with regard to an action in progress.20.1 (p. 96)Tu padre debe (de) estar descansando.Your father must be having a rest.Deben (de) estar durmiendo.They must be sleeping.21.2 (p. 100); 48.1.9 (p. 287)50.1.5The future, future perfect and conditional in the expression of probabilitySupposition or probability with regard to something in the present or the past, can beexpressed with verb forms other than those most frequently associated with the presentand past. Note these examples:Estará en casa.He/she must be at home now.Habrán salido.They must have gone out.Sería medianoche.It must have been midnight. (p. 76); 17.6 (p. 77); 17.7 (p. 77); 48.1.10 (p. 287); 48.1.11 (p. 287)29817.5.2