on the whole natural, determined by the biological gender of the creature. However, exactly speaking, the gender here means the grammatical gender, which includes feminine, masculine and neuter. (3) Case is an inflectional category, basically of nouns, which typically marks their roles in relation to other parts of the sentence. In English, pronouns have three cases of nominative (e.g. we, he, she), accusative (e.g. us, him, her) and genitive (e.g. our, your, his). But nouns have only two cases: general (e.g. Tom, girl) and genitive (e.g. Tom’s, girl’s). (1) 数是用来分析词类的语法范畴，有单数、双数和复数等。在英语中，数主要是名词的范畴，包括两种形式：单数和复数。数还