This document shall specify, for a crack inspection, the minimum size crack expected to be discovered or, if no minimum is defined, a statement to this effect.
答案解析
解析：
这道题考察的是关于裂纹检测中最小裂纹尺寸的规定。选项B正确地表达了这一要求，即文件应该规定裂纹检测中预期发现的最小允许裂纹尺寸，如果没有规定最小尺寸，则应该有一个同样有效的标准。选项A虽然表达了类似的意思，但是没有完全准确地描述规定的内容。选项C则表述了一些不相关的内容，与题目要求不符。
生活中，我们可以通过类比来理解这个知识点。就像我们在购买水果时，商家会规定水果的最小尺寸，如果没有规定，可能会有一个行业标准来参考。这样可以确保消费者能够得到符合期望的产品。在工程领域，规定最小裂纹尺寸也是为了确保检测的准确性和可靠性。
相关知识点：
文档要明确裂纹检查最小尺寸
相关题目
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