The examples in (85) show that R-extraction is possible if the adpositional phrase acts as a PP-complement or as a complementive. Example (85a) shows that R-extraction from the complement of the verb wachten'to wait' is possible; witness the fact that the adverbial phrase de hele dag'the whole day' can intervene between the R-pronoun and the preposition op. Example (85b) shows that R-extraction is also possible from PPs that act as complementives, as is clear from the fact that the accusative object het boek'the book' can intervene between the R-pronoun and the preposition in.

Adverbially used adpositional phrases, on the other hand, generally do not allow R-extraction, which is illustrated by the examples in (86); the (b)-examples show that, despite the fact that R-pronominalization of the temporal voor-PP is fully acceptable, R-extraction gives rise to an unacceptable result.

The examples in (85) and (86) suggest that R-extraction is only possible with PP-complements and complementives. This would be in line with a generalization from the generative literature (which was formulated as part of Huangʼs (1982) Condition on Extraction Domains) according to which adjuncts are islands for extraction. There is, however, a group of adpositional phrases that are traditionally analyzed as adverbial clauses that do nevertheless allow R-extraction. This is illustrated in (87), for an instrumental PP headed by met 'with' ; see Section 5.2.1, sub IIIA, for more PPs of this sort.

This may give rise to two possible conclusions: either we assume the generalization that only PP-complements and complementives can undergo R-extraction is wrong, or we have to assume that instrumental PPs actually function as a kind of complement of the verb, albeit that they differ from PP-arguments like op een bericht in (85a) or predicative complements like in de kast in (85b) in not being obligatorily. Here we will leave the question of which alternative is correct open.
      Besides the requirement that the adpositional phrase must be a complement, a complementive, or involve a specific semantic role (like instrumental met), it must also occupy a certain position in the clause in order to license R-extraction: the stranded preposition must be left-adjacent to the verb(s) in clause-final position (with some qualifications that will follow below). This is illustrated in (88) by means of the pronominalized form of the instrumental PP met een breekijzer from (87); R-extraction is possible if the pronominalized PP daarmee is left-adjacent to the clause-final verbs but not if it precedes the negative adverb niet or if it is placed in a position following the clause-final verbs.