h3
　　　　黄色➜ p:nth-child(2)
　　　　赤 ➜ p:nth-of-type(2)

pspanspan2

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selectorexampleexample description
:nth-child(n) p:nth-child(2) { background: #ff0000; } Specify a background color for every <p> element that is the second child of its parent:
:nth-of-type(n) p:nth-of-type(2) { background: #ff0000; } Specify a background color for every <p> element that is the second p element of its parent:

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