1<p [ngClass]="'first second'">...</p>
2
3<p [ngClass]="['first', 'second']">...</p>
4  
5<p [ngClass]="{'first': true, 'second': false}">...</p>
6  
7<p [ngClass]="stringExp|arrayExp|objExp">...</p>
8  
9<p [ngClass]="{'class1 class2 class3' : true}">...</p>