\label{fig:variation}
Variation with the centre-of-mass energy of the statistical uncertainties of the five top-quark electroweak form factors considered in Ref.~\cite{Baer_2013}, at the FCC-ee. Left column, from top to bottom: $F_{1V}^\gamma$, $F_{1V}^Z$, and $F_{1A}^Z$. Right column: $F_{2V}^\gamma$ and $F_{2V}^Z$.