it right now. Modal uses of the preterite form would include: Would is used in some conditional sentences. Expression of politeness, as in I would like... (for "I want") and Would you (be so kind as to) do this? (for "Please do this"). As a tense marker would is used as Future of the past, as in I knew I would graduate two years later. This is a past form of future will as described above under . (It is sometimes replaced by should in the first person in the same way that will is replaced by shall.) As an aspect marker, would is used for Expression of habitual aspect in past time, as in Back then, I would eat early and would walk to school. Both will and would can be used with the perfect infinitive (will have, would have), either to form the future perfect and conditional perfect forms already referred to, or to express perfect aspect in their other meanings (e.g. there will have been an arrest order, expressing strong probability). The negated forms are will not (often contracted to won't) and would not (often contracted to wouldn't). In the modal meanings of will the negation is effectively applied to the main verb phrase and not to the modality (e.g. when expressing an order, you will not do it expresses an order not to do it, rather than just the absence of an order to do it). For contracted forms of will and would themselves, see above. Must and have to The modal must expresses obligation or necessity: You must use this form; We must try to escape. It can also express a conclusion reached by indirect evidence (e.g. Sue must be at home). An alternative to must is the expression have to or has to depending on the pronoun (in the present tense sometimes have got to), which is often more idiomatic in informal English when referring to obligation. This also provides other forms in which must is defective (see above) and enables simple negation (see below). When used with the perfect infinitive (i.e. with have and the past participle), must has only an epistemic flavor: Sue must have left means that the speaker concludes that Sue has left. To express obligation or necessity in the past, had to or some other synonym must be used. The formal negation of must is must not (contracted to