Of these, all but [13] take post-head noun phrase complements, a feature of verbs but not nouns. While the painting in [13] does not take a noun phrase complement, it is modified by an adverb phrase (silently), a feature typical of verbs that is also present in [5] and [9]. The troublesome cases are the ones represented by the paintings in [5]–[9], which demonstrate features of both nouns and verbs. These are often called gerunds (though the terminology can vary). The paintings in [5]–[9] are noun-like in that they are the heads of phrases functioning as either subject of direct object. The paintings in [5] and [6] are even more noun-like in that they occur with the determinative Brown's. However, the paintings in [5]–[9] are also verb-like in that they take a post-head noun phrase complement. The painting in [9] is even more verb-like in that it is modified by the adverb phrase deftly. Linguists have offered a variety of accounts for English gerunds. For instance, Geoffrey K. Pullum and James P. Blevins both argue that gerunds are noun phrases with verb phrase heads. Other linguists, such as Richard Hudson, argue that gerunds are both verbs and nouns. Yet others, such as Bas Aarts, argue that the fact that gerunds tend to occur in the same places as noun phrases (as subject, direct object, and so on) is not enough to support that they occur within noun phrases and instead treat them as verbs that happen to be in non-canonical positions. Adverbs There is typically little confusion between nouns and adverbs in English because there is no overlap in the inflectional morphology that they take (-s for nouns, -er and -est for adverbs) and they tend to cooccur with different kinds of words (e.g., nouns can head phrases containing determinatives while adverbs cannot). Further, nouns and adverbs tend to head phrases with different prototypical functions: noun phrases typically function as subjects, direct objects, and indirect objects while adverb phrases typically function as adjuncts. Despite no overlap in the form and distribution of nouns and adverbs, some linguists suggest gradience between a certain class of nouns and adverbs. For example, Barbara M. H. Strang notes that words such as yesterday and today have features of both nouns and adverbs. They are noun like in that they can occupy typical noun phrase positions and head possessive noun phrases (e.g., yesterday's news), but