Can't bind to 'ngIf' since it isn't a known property of 'ion-grid' code example

Example 1: Can't bind to 'ngModel' since it isn't a known property of 'input'

import { FormsModule } from '@angular/forms';

[...]

@NgModule({
  imports: [
    [...]
    FormsModule
  ],
  [...]
})

Example 2: Can't bind to 'ngForOf' since it isn't a known property of 'div'.

// older Angular versions
// import {BrowserModule, CommonModule} from '@angular/common';

import { BrowserModule } from '@angular/platform-browser'
..
..
@NgModule({
  imports: [BrowserModule, /* or CommonModule */],
  ..
})