impersonal pronoun
noun/ɪmˌpɜːsənl ˈprəʊnaʊn/
/ɪmˌpɜːrsənl ˈprəʊnaʊn/
(grammar)- a pronoun (in English, the pronoun ‘it’) that does not refer to a person or thing or to any other part of the sentence, for example in ‘it was raining’
非人称代词（如 it was raining 中的 it）