One is on the left and the other is on the right. How to do this layout with flex?

the three red ones are adjacent.
structure:

div.flex
  div.box
  div.box
  div.box
Mar.13,2021

this is not called one on the left and one on the right, it should be: "two-column layout, adaptive width, right?"

   

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MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b37fdc-2c0cf.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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