or expectations: This should work. In these uses it is equivalent to ought to. Both shall and should can be used with the perfect infinitive (shall/should have (done)) in their role as first-person equivalents of will and would (thus to form future perfect or conditional perfect structures). Also shall have may express an order with perfect aspect (you shall have finished your duties by nine o'clock). When should is used in this way it usually expresses something which would have been expected, or normatively required, at some time in the past, but which did not in fact happen (or is not known to have happened): I should have done that yesterday ("it would have been expedient, or expected of me, to do that yesterday"). The formal negations are shall not and should not, contracted to shan't and shouldn't. The negation effectively applies to the main verb rather than the auxiliary: you should not do this implies not merely that there is no need to do this, but that there is a need not to do this. The logical negation of I should is I ought not to or I am not supposed to. Will and would Will as a tense marker is often used to express futurity (The next meeting will be held on Thursday). Since this is an expression of time rather than modality, constructions with will (or sometimes shall; see above and at shall and will) are often referred to as the future tense of English, and forms like will do, will be doing, will have done and will have been doing are often called the simple future, future progressive (or future continuous), future perfect, and future perfect progressive (continuous). With first-person subjects (I, we), in varieties where shall is used for simple expression of futurity, the use of will indicates particular willingness or determination. (Future events are also sometimes referred to using the present tense (see Uses of English verb forms), or using the going to construction.) Will can express habitual aspect; for example, he will make mistakes may mean that he frequently makes mistakes (here the word will is usually stressed somewhat, and often expresses annoyance). Will also has these uses as a modal: It can express strong probability with present time reference, as in That will be John at the door. It can be used to give an indirect order, as in You will do