A compound subject consists of two or more individual noun phrases coordinated to form a single, longer noun phrase. Compound subjects cause many difficulties in compliance with grammatical agreement between the subject and other entities (verbs, pronouns, etc.). These issues also occur with compound noun phrases of all sorts, but the problems are most acute with compound subjects because of the large number of types of agreement occurring with such subjects. For English compound subjects joined by and, the agreement rules are generally unambiguous, but sometimes tricky. For example, the compound subject you and I is treated equivalently to we, taking appropriate pronominal agreement ("our car", not "your car", "their car", etc.). In languages with more extensive subject-verb agreement (e.g. Spanish or Arabic), the verb agreement is clearly revealed as also being first-person plural. Compound subjects joined by and generally take a plural verb. However, there are exceptions. When compound subjects are thought of as a single unit, a singular verb is used, e.g. Peanut butter and jelly is available in the cafeteria. As shown in the examples, if the subjects are joined by or, the rules are often ill-defined, especially when two elements that differ in grammatical gender or grammatical number are coordinated. The tendency, in such cases, is to rewrite the sentences to avoid the conjunction: e.g. "Sylvia and I each have our own car, and one of us is planning to sell their car". This still has a compound subject using and as the conjunction, and uses "semi-informal" "generic their" to get around the "his or her" problem. This could be avoided with a further rewrite: "Either Sylvia will sell her car, or I will sell mine." Examples Jack and Jill went up the hill. Haley and I went to the park. John and Jill are coming to visit. John or Jill is coming to visit. (Better with "either") My sisters or my mother is/are coming to visit. (Rewrite as "Either my sisters are coming to visit, or my mother is.") My mother or father is coming to visit. John and I are going to sell their car. You and John are going to sell your (you guys', your own) car. John and I are going to sell our cars. (ambiguous between whether we own two cars jointly, or each owns one car individually) John or Jim is going to sell their car. (i.e. they jointly own