A lone pair of electrons takes up space despite being very small. Lone pairs have a greater repulsive effect than bonding pairs. This is because there are already other forces needing to be taken into consideration with bond pairs.
So to summarize: Lone pair-lone pair repulsion > lone pair-bond pair repulsion > bond pair-bond pair repulsion. This makes the molecular geometry different.
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At least one pair, or one pair? If it is one pair, then it depends if the shape is regular or irregular.
shape no pairs of perpendicular sides
Trapezium
That shape would be a trapezoid.
A trapezoid.