What is the meaning that the result of practice is the only and last measure or mark of truth?

实践结果是检验认识真理性的唯一最终的尺度或标志，这是什么意思？

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Read engineering and architectural drawings, sketches and work specifications to be performed, and lay out, measure and mark sheet metal according to drawings or templates.

阅读工程和建筑图纸，草图和要执行的工作规范，根据图纸或模板划线，测量和标记钣金。

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Most observers say they have failed to make a mark since their return, but in the absence of professional pollsters it is almost impossible to measure party or personal popularity in the run-up to the election.

ECONOMIST: Libya��s election