$ 解： \because \widehat{B C}=80^{\circ}$
$ \therefore \angle A=40^{\circ}$
$ \because \angle C E B=60^{\circ}$
$ \therefore \angle A E C=180^{\circ}-60^{\circ}=120^{\circ}$
$ \therefore \angle C=180^{\circ}-120^{\circ}-40^{\circ}=20^{\circ}$
$ \therefore \widehat{ A D}=40^{\circ}.$
