Multiple ExpansionTile with multiple ListTile, how to do a second one - flutter

Question

This question might sound dumb, but I am trying to make a list of Expandable list items which in turn have a list of items inside. I have come this far but I am unable to make it a show a second one WITHOUT USING INDEX.
import 'package:flutter/material.dart';
class ExerciseScreen extends StatefulWidget {
const ExerciseScreen({Key? key}) : super(key: key);
#override
State<ExerciseScreen> createState() => _ExerciseScreenState();
}
class _ExerciseScreenState extends State<ExerciseScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Table of Contents CEFR'),
),
body: ListView(
children: const [
ExpansionTile(
leading: Padding(
padding: EdgeInsets.all(8.0),
child: CircleAvatar(
backgroundColor: Color.fromARGB(255, 0, 182, 91),
child: Text(
'A1',
style: TextStyle(fontSize: 15, color: Colors.white),
),
),
),
title: Text(
'To be: is, am, are',
style: TextStyle(fontSize: 21, color: Colors.black),
),
children: [
ListTile(
leading: CircleAvatar(
child: Text('A1'),
),
title: Text('Affirmative ideas'),
subtitle: Text('Singular and plural subjects'),
),
ListTile(
leading: CircleAvatar(
child: Text('A1'),
),
title: Text('Are: plural verb'),
subtitle: Text('Positive ideas using plural subjects'),
),
ListTile(
leading: CircleAvatar(
child: Text('A1'),
),
title: Text('Is : singular verb'),
subtitle: Text('Positive ideas using singular subjects'),
),
ListTile(
leading: CircleAvatar(
child: Text('A1'),
),
title: Text('Questions'),
subtitle: Text('Interrogative ideas - subject/verb/switch '),
),
ListTile(
leading: CircleAvatar(
child: Text('A1'),
),
title: Text('Questions'),
subtitle: Text('Closed questions (yes/no)'),
),
],
),
],
),
);
}
}

Answer 1

What is the problem with just adding a second ExpansionTile to your list? Like so:
import 'package:flutter/material.dart';
class ExerciseScreen extends StatefulWidget {
const ExerciseScreen({Key? key}) : super(key: key);
#override
State<ExerciseScreen> createState() => _ExerciseScreenState();
}
class _ExerciseScreenState extends State<ExerciseScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Table of Contents CEFR'),
),
body: ListView(
children: const [
ExpansionTile(...),
ExpansionTile(...),
],
),
);
}
}
On my side it shows both ExpansionTiles correctly: