Edit in JSFiddle

<div ng-app>
    <select ng-model="city">
        <option value="taipei">台北</option>
        <option value="tainan">台南</option>
    <select>    
    <div ng-show="city == 'taipei'">你選了台北</div>
    <div ng-show="city == 'tainan'">你選了台南</div>       
</div>