Present participles can be used as supplementive-I and as supplementive-II, as shown in (148). Note, however, that in (148b) only the simultaneity reading is possible; the conditional reading associated with supplementive-II (Whenever Jan is in the library, he works) is not available. Instead, the example is habitual (Jan always works).

The present participle in (148a) expresses durative aspect and can therefore be considered to be verbal; in this respect, it differs from its complementive counterpart, which is truly adjectival. This categorial difference explains why intransitive, transitive, and unaccusative present participles can be used as supplementives, but not as complementives (cf. Table 7 in Section 31.3.1, sub II). Some examples are given in (149).

Haeseryn et al. (1997) has observed that the durative meaning of an activity-denoting present participle can be emphasized by placing the word al in front of it. Another result of adding this element seems to be that the present participle must refer to a continuous, uninterrupted action. This is very clear from example (150), taken from Jansen and Lentz (2002), which is typically found in recipes.

The construction with al has not been studied extensively, but it seems to behave differently from the present participle constructions in (149) in several ways. First, in the construction with al, the present participle can optionally be followed by an -e ending, which would lead to a highly marked result with the present participles in (149); at best, these examples would be judged as archaic. Second, the examples in (151) show that the al + participle construction can never be preceded by the direct object of the participle, while this seems possible in the absence of al. This is also clear from example (150), where the direct object of the transitive verb roerento stir is left implicit: it is the syntactic context (here: the presence of the aan-PP) that makes it clear that it is the soup that is being stirred.

Similarly, the examples in (152a&b) show that the construction with al cannot be accompanied by a PP-complement, while this is easily possible in the absence of al. Note, however, that the result with al seems to improve slightly when the PP-complement follows the present participle.

Finally, the examples in (153) show that these co-occurrence restrictions do not only apply to arguments of the verb, but also seem to apply to adverbial modifiers; while present participles can normally be preceded by e.g. manner adverbs, this produces a degraded result in the al + participle construction.

The restrictions on the al + participle construction suggest that the present participle has lost at least some of its verbal properties. For lack of information, we will not dwell on the question regarding the categorial status of the present participle and leave it to future research.

The examples in (154) show that past/passive participles behave more or less the same way as present participles: they can be used both as supplementive-I and as supplementive-II, although the latter only expresses the simultaneity reading, as is clear from the fact that (154b) simply expresses that Emil is often punished.

We have not been able to construct examples in which modal infinitives are used in either of the two supplementive functions.