Along with these three properties, the class will have a number of methods for adding elements to the history stack, retrieving items, and saving the stack data to browser cookies.

除了这三个属性外，该类还需要一些方法来添加元素、检索堆栈数据以及将堆栈数据保存到浏览器cookie中。

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It involves adding up all the points pupils achieved in the three subjects, then dividing this by the number of pupils eligible to take the tests.

BBC: NEWS | UK | Education | Guide to the primary school tables

Many observers have suggested that adding at least three women to any type of team effort improves performance because a non-token number (three) counters group think, one of the greatest obstacles to creativity and innovation.

FORBES: Speak Up! More Women Make Team Smarter