(Un)fortunately you can‘t; the ngSwitch is quite “dumb” if you look at the source code: it‘s just a === between the case value and the switch value. You have two options, but both of them are far from great.
Option 1 is using the directive *ngSwitchDefault, but this will only work if all your multiple cases are FORM 1:
<div [ngSwitch]="data.type">
<div *ngSwitchDefault>FORM 1</div>
<div *ngSwitchCase="'range'">FORM 2</div>
</div>
The other option, which is quite verbose, is doing something like this:
<div [ngSwitch]="data.type">
<div *ngSwitchCase="data.type === 'multi-choice' || data.type === 'singe-choice' ? data.type : '' ">FORM 1</div>
<div *ngSwitchCase="'range'">FORM 2</div>
</div>