The ? character means to match zero or one instance of the previous pattern element; the * character means to match zero or more of the previous element.

字符表示匹配前面模式元素的零个或一个实例，* 字符表示匹配前面元素的零个或多个实例。

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The plus sign at the end means "match one or more of the last thing" (the asterisk is for "zero or more", and the question-mark is for "zero or one").

结尾处的加号表示“查找最后字符串的一个或多个匹配”(星号表示“零个或多个”，问号表示“零个或一个”)。

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With short-term policy rates at or near zero, getting more of a monetary boost means expanding a set of instruments whose efficacy, and side-effects, are ill-understood (see article).

由于短期政策利率接近或已经达到零，因此获得更多的货币提振意味着扩展一系列手段，而这些手段的效果和副作用却并不知道。

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