different types of something, a count form is available for almost any noun (e.g., This shop carries many cheeses. = "many types of cheese"). Non-count nouns denote things that, when put together, remain the same thing. For example, if I have luggage and you give me more luggage, I still just have luggage. Count nouns fail this test: if you have an apple, and I give you more apple or more apples, you no longer just have an apple. Modern English marks a division between singular and plural number. (Old English pronouns also marked the dual number.) Singular number restricts the denotation of the noun to the set of singularities. Plural number is often said to mean more than one, but, in fact, it restricts the denotation of the noun to the set of non-singularities. That is, in English, plural nouns are appropriate for quantities denoted by all the real numbers, including 0 and other quantities smaller than 1, except exactly ±1. The semantic number and grammatical number of a particular NP may not match. For example, with collective nouns such as committee, which denote a unit composed of multiple individuals, agreement can either be singular because the noun is morphologically singular (e.g., The committee has not yet come to a decision) or plural because it is semantically plural (e.g.,The committee have not yet come to a decision). Gender and animacy Modern English has lost the system of grammatical gender that was present in Old English, and while there is some disagreement over what has replaced it, generally speaking English is said to have a system of "natural gender", which applies only to the pronouns. A natural gender is one "in which there is a clear correlation between masculine and feminine nouns and biological traits in the referent." But whether this accurately characterizes the English gender system is disputed. The Cambridge Grammar of the English Language argues that English has a "weakly grammaticalized" gender, which is based only on pronoun agreement. This gender system involves two subsystems: one involving the distinctions between the personal pronouns he, she, and it and another involving the distinctions between the relative pronouns who and which. In the personal pronoun subsystem, nouns can be classified according to whether they are compatible with one, two, or three of these three personal pronouns. Single-gender and dual-gender nouns can be subclassified according to which specific pronouns they agree