单语范例（未经PONS编辑处理）
This cover was a touchstone for the new musical sub-genre of rap rock, or the melding of rock and hip hop.
en.wikipedia.org The most notable is the single-stage crystal oscillator circuit, which became the touchstone of the electronics communication art.
en.wikipedia.org Throughout their disagreements, they still stayed close, remaining each other's touchstones.
en.wikipedia.org Many philosophical schools have at their core one particular thinker or even one central work which serves as a canonical touchstone.
en.wikipedia.org One touchstone of the authentic fairy tale is that it is presented as wholly credible.
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