In choosing a method for determining climatic conditions that existed in the past, paleoclimatologists invoke four principal criteria.

在选择确定过去存在的气候条件的方法时，古气候学家援引了四个主要标准。

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In this case an instance lock is acquired four times: three times for the append method and one time for the toString method, right after another.

在上面的例子中，锁的实例会被请求四次：前三次是执行append方法，最后一次是执行toString方法，紧接着前一个。

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Create getters and setters for the four fields by following the method shown in Listing 1 for the symbol field.

按照清单1中显示的用于symbol字段的方法为以上4个字段创建getter和setter。

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They also include the Rocket Stove built out of an old fuel can and the four-folded sari method in Bangladesh to remove cholera.

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