To be ill-suited or incompatible; like a square peg in a round hole.
他俩的性格完全不同，在一起简直是圆孔方木，怎么也合不来。
Their personalities are completely different; being together is like a square peg in a round hole, they just can't get along.
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To be ill-suited or incompatible; like a square peg in a round hole.