The examples in (137) show that present participles can be used both as supplementive-I and as supplementive-II. It should be noted, however, that in (137b) only the simultaneity reading is possible. The conditional reading associated with supplementive-II (Whenever Jan is in the library, he is working) is not available: instead, the example is habitual (Jan is always working).

The present participle in (137a) expresses durative aspect, and can therefore be considered verbal; in this respect, it differs from complementives, which are always truly adjectival. This categorial difference accounts for the fact that although intransitive, transitive and unaccusative present participles cannot be used as predicative complementives (see Table 7 in 9.3.1, sub IIE), they can be used as supplementives. Some examples are given in (138).

      Haeseryn et al. (1997) observe that the durative meaning of an activity-denoting present particle 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 (139), taken from Jansen and Lentz (2002), which can readily be found in recipes.

The construction with al has not been extensively studied, but it seems that it behaves differently in various respects from the present participle constructions in (138). We will not digress on whether or not the head of this construction can be considered a regular present participle, but leave this question to future research and simply discuss some of these differences. First, the participle in the construction with al can be optionally followed by an -e ending, which would give rise to a highly marked result with the present participles in (138); at best, these examples would then be judged as archaic. Second, the examples in (140) 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 (139), in which the direct object of the transitive verb roeren'to stir' is left implicit: it is the syntactic context that makes clear that it is the soup that is stirred.

Similarly, the examples in (141a&b) show that the construction with al cannot be accompanied by a prepositional complement, while this is easily possible in the absence of al. It should be noted, however, that the result with al seems to improve if the PP-complement follows the present participle.

The examples in (142), finally, show that these co-occurrence restrictions apply not only to arguments of the verb, but also seem applicable to adverbial modifiers; whereas present particles can normally be preceded readily by, e.g., manner adverbs, this gives rise to a degraded result in the al + participle construction.

The examples in (143) show that past/passive participles behave more or less the same as present participles: they can be used both as supplementive-I and as supplementive-II, although the latter expresses only the simultaneity reading, as is clear from the fact that (143b) simply expresses that Emil is punished often.

We have not been able to construct examples in which modal infinitives are used in either supplementive function.