zijn, vallen and staan + te + infinitive for can and must

De beschadigde scan is nog te herstellen. (The damaged scan can still be repaired.) The infinitive herstellen looks active, but de beschadigde scan is the thing that someone could repair.

Put the thing affected by the action before zijn, then add te + infinitive; use vallen in certain impersonal patterns and staan only in a small set of fixed expressions.

1. Start with an active idea: Een monteur kan de lift repareren. (A mechanic can repair the lift.)
2. Leave the person doing the action unspoken and make the affected thing the subject: de lift.
3. Conjugate zijn and add te + infinitive: De lift is te repareren. (The lift can be repaired.)
4. In a subordinate clause, keep the infinitive before the final form of zijn: We blijven open omdat de lift snel te repareren is. (We will stay open because the lift can be repaired quickly.)

This form is often called a modal or passive infinitive. It expresses possibility, necessity, or a related judgement without building an ordinary passive with worden.

The subject of zijn normally matches the object of the corresponding active sentence: it receives the action instead of performing it.

The regular pattern therefore works best with a verb that can act on an object. Fixed impersonal expressions such as Er valt hier weinig te lachen. (There is little to laugh about here.) form a limited extension and should be learned with their full frame.

Predicative X is te + infinitive normally expresses ability or possibility; attributive forms before a noun can also express an obligation, while a small set of evaluative expressions conveys advice, hope, or fear.

Context decides between can and must in an attributive form. het te betalen voorschot (the advance that must be paid) can name a required payment, while een niet te negeren waarschuwing (a warning that cannot be ignored) describes practical necessity. The infinitive itself does not supply a fixed degree of necessity.

Use vallen + te + infinitive for possibility in a limited set of patterns, often with er, a prepositional phrase, negation, or a quantity word.

• Er valt genoeg te bespreken. (There is enough that can be discussed.)
• Aan de planning valt niets meer te veranderen. (Nothing else can be changed in the schedule.)
• Dat valt moeilijk te bewijzen. (That is difficult to prove.)

Learn staan + te as fixed combinations rather than as a free alternative to zijn: te wachten staan (to lie ahead), te gebeuren staan (to be about to happen), te doen staan (to be something someone must do), and te bezien staan (to remain uncertain). In Het appartement staat te koop. (The apartment is for sale.), koop is a noun rather than an infinitive, so the phrase does not belong to this construction.

Put zijn in the simple past for an earlier viewpoint: De extra reistijd was te verwachten. (The extra travel time could be expected.) Keep the modal infinitive as te + infinitive; do not replace it with a past participle.

• Use zijn + te + infinitive to assess whether an object can be handled, read, repaired, reached, or understood.
• Use an attributive modal infinitive before a noun in plans, rules, and formal instructions: de nog te beantwoorden vragen (the questions that still need to be answered).
• Use the established vallen and staan frames when they fit; treat them as narrower patterns than general zijn + te.
• Use worden + past participle when you state that an event happens, and moeten + worden when you give an unambiguous requirement.

• Do not treat the surface subject as the person doing the action. De code is te controleren. (The code can be checked.) Someone checks the code; the code does not check anything.
• Do not add om. This modal infinitive uses te controleren, while a purpose or complement clause may use om te.
• Do not use ordinary predicative zijn + te as a firm command when moeten worden says the requirement clearly: Het formulier moet vandaag worden ondertekend. (The form must be signed today.)
• Do not invent new staan + te combinations. The productive ability pattern uses zijn; staan survives in a small group of expressions.

Review ordinary te-infinitives, compare the passive voice, and keep this pattern separate from the bare infinitive and om + te clauses.