construction that uses a (non-impersonal) adverb rather than a verb. Forms Invisible arguments When an agent is unspecified, impersonal verbs are also known as zero person construction, or impersonal construction. An implicit argument (an argument that is put forth without stating it directly) is present on a semantic level for both Estonian and Finnish. The Finnic impersonal construction enables an event or state to be described without specifying the identity of the agent (actor). Despite this, the interpretation of the impersonal includes a referent of some sort (dummy). The zero person is not entirely the same as an impersonal. Finnish: Estonian: There is a lack of an overt nominative subject in these constructions. By-phrase Some languages require their counterpart to the English by-phrase be present (like Palauan and Indonesian, Austronesian languages). Other languages disallow the presence of a by-phrase. For example, Polish does not allow the use of a by-phrase in its passive. The content in the parenthesis causes the Polish sentence to be ungrammatical as who did the knocking cannot be overtly stated. As such, it might seem like it would be more grammatical to use impersonal verbs in such cases. Impersonal verbs by language In some languages such as English, French, German, Dutch and Swedish, an impersonal verb always takes an impersonal pronoun (it in English, il in French, es in German, het in Dutch, det in Swedish) as its syntactical subject: It snowed yesterday. (English) Il a neigé hier. (French) Es schneite gestern. (German) Het sneeuwde gisteren. (Dutch) Det snöade igår. (Swedish) Occasionally an impersonal verb will allow an object to appear in apposition to the impersonal subject pronoun: It is raining diamonds. Or as an instrumental adjunct: It was pouring with rain. (British English) In some other languages (necessarily null subject languages and typically pro-drop languages), such as Portuguese, Spanish, Occitan, Catalan, Italian, Romanian, in Hungarian and all the Slavic languages, an impersonal verb takes no subject at all, but it is conjugated in the third-person singular, which is much as though it had a third-person, singular subject. Nevó ayer. (Spanish) Nevou ontem. (Portuguese) Ha nevicato ieri. (Italian) A nins ieri. (Romanian) Sniježilo je jučer. (Croatian) Havazott tegnap. (Hungarian) Вчера вееше снег. / Včera veeše sneg. (Macedonian) Other languages, those which require a subject, may permit an adjunct to assume that role. Unfortunately the next day poured with rain. Indo-European English The following sentences illustrate impersonal