使用SingleChildScrollView时无法向下拖动底部表单

我已经创建了一个带有底部表和列表视图构建器的应用程序。在底部，当我将其向上拖动时必须出现一个文本按钮底部表必须出现。底页上有一个表格。我用 SingleChildScrollView 包裹了底页。但是当我单击 TextFormField 键盘时，我可以滚动底部工作表。但是我无法将其向下拖动并关闭底部工作表。即使我按下手机中的后退箭头以摆脱键盘。

import 'package:flutter/material.dart';

class Home extends StatefulWidget {
  const Home({Key key}) : super(key: key);

  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {

  @override
  Widget build(BuildContext context) {
    var width = MediaQuery.of(context).size.width;
    return Scaffold(

        resizeToAvoidBottomInset: false,
        body: Stack(
                children: [
                  ListView.builder(
                      itemCount: 1,
                      itemBuilder: (context, index) {
                        return Card(
                          );
                      }),
                  Positioned(
                    bottom: 0,
                    child: GestureDetector(
                      onPanEnd: (details) {
                        if (details.velocity.pixelsPerSecond.dy < 10) {

                          //Bottom Sheet.................................................................................................................

                          showModalBottomSheet(
                              shape: RoundedRectangleBorder(
                                borderRadius: BorderRadius.vertical(
                                    top: Radius.circular(25)),
                              ),
                              backgroundColor: Colors.green,
                              context: context,
                              builder: (context) {
                                return SingleChildScrollView(
                                  child: Container(
                                    padding: EdgeInsets.all(10),
                                    child: Form(
                                        child: Column(
                                          children: [
                                            Icon(Icons.arrow_drop_down),
                                            Text("Drag down to Close"),

                                            Container(
                                              color: Colors.red,
                                              child: Column(
                                                children: [
                                                  Row(
                                                    children: [
                                                      Expanded(
                                                        child: TextFormField(
                                                          decoration: InputDecoration(
                                                            labelText: "Current amount",
                                                          ),
                                                        ),
                                                      ),
                                                    ],
                                                  ),
                                                  Row(
                                                    children: [
                                                      Expanded(
                                                          child: TextButton(
                                                              onPressed: () {},
                                                              child: Text("Submit"))),
                                                    ],
                                                  ),
                                                ],
                                              ),
                                            ),
                                          ],
                                    )),
                                  ),
                                );
                              });
                          // Bottom Sheet Ends ......................................................................................................................................................
                        }
                      },
                      child: Container(
                        color: Colors.blue,
                        width: width,
                        padding: EdgeInsets.all(10),
                        child: Column(
                          children: [
                            Icon(Icons.arrow_drop_up),
                            Text("Drag up to Enter an Account"),
                          ],
                        ),
                      ),
                    ),
                  )
                ]),
        );
  }
}