When all the elements in a series connected by ‘or’ are singular, the verb they govern is singular: Tom or Jack is coming. Beer, ale, or wine is included in the charge. When all the elements are plural, the verb is plural. When the elements do not agree in number, some grammarians have suggested that the verb should agree in number with the nearest element: Tom or his sisters are coming. The girls or their brother is coming. Cold symptoms or headache is the usual first sign.Other grammarians, however, have argued that such constructions are inherently illogical and that the only solution is to revise the sentence to avoid the problem of agreement: Either Tom is coming or his sisters are. The usual first sign may be either cold symptoms or a headache.
a or b + is , 这里a, b 都是单数。这很简单，两者中的一个。无论用什么原则，都接单数。
a or b + ？ , 这里a, b 有一个是复数，这个存在争议！！！有语法家建议使用就近原则。举个例子：Tom or his sisters are coming. / His sisters and Tom is coming. 但有些语法家认为这中句式存在逻辑问题，本人也认为存在逻辑问题，a (or) b 这两个是对等的，如果其中一个是复数，一个是单数，则不对等。换成中文则非常明显：一个苹果或者一筐梨子是奖品。既然是选择，就应该去除掉无关变量，例如数量。所以正确的说法应该是一个苹果或者一个梨子是奖品。所以，这里的唯一解决办法是改变句式。
a or b + are, 这里a, b 都是复数。这很简单，无论用什么原则，都接复数。