The Cache header does not work. <metahttp-equiv = "Cache-Control" content = "max-age = 7200"/> What should I do?

The Cache header does not work & lt; metahttp-equiv & quot; Cache-Control & quot; content & quot; max-age7200 & quot; & gt; if you have any questions, please add this sentence on the html page. I don't know why. & lt; metahttp-equiv & quot; Cache-Control & quot; content & quot; m Cache header does not work.
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Adding this sentence to the html page is useless. I don't know why.


Or is there any way to control the cache time of a single static page?


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How do you use
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It seems that this parameter does not play any role. it is rarely used to see if someone else can help you. Sorry
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You can try this.
For specific usage, refer to the header in the PHP Manual
Header ('last-Modified: '. gmdate ('d, d m y h: I: S', $ time). 'gmt ');