问题
I tried to use selectedIndex and it opens only one item default. I would like to open 2 or more items in Material Stepper by default. I have an example (https://stackblitz.com/edit/ng-mat-beta-12-luhe7n?file=app%2Fapp.component.ts). I would like to open without the timeout and 2 or 3 items by default. I would appreciate any help.
来源：https://stackoverflow.com/questions/55936137/how-to-set-2-default-open-items-in-material-stepperangular