嗨，我试图建立一个扑扑的登录屏幕，但打开它时出现错误。

找不到材料小部件文本字段小部件需要材料小部件祖先

 import 'package:flutter/material.dart';

 Widget LoginPage() {
    return new Container(
      height: MediaQuery.of(context).size.height,
      decoration: BoxDecoration(
        color: Colors.white,
        image: DecorationImage(
          colorFilter: new ColorFilter.mode(
              Colors.black.withOpacity(0.05), BlendMode.dstATop),
          image: AssetImage('assets/images/mountains.jpg'),
          fit: BoxFit.cover,
        ),
      ),
      child: new Column(
        children: <Widget>[
          Container(
            padding: EdgeInsets.all(120.0),
            child: Center(
              child: Icon(
                Icons.headset_mic,
                color: Colors.redAccent,
                size: 50.0,
              ),
            ),
          ),
          new Row(
            children: <Widget>[
              new Expanded(
                child: new Padding(
                  padding: const EdgeInsets.only(left: 40.0),
                  child: new Text(
                    "EMAIL",
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                      color: Colors.redAccent,
                      fontSize: 15.0,
                    ),
                  ),
                ),
              ),
            ],
          ),
          new Container(
            width: MediaQuery.of(context).size.width,
            margin: const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
            alignment: Alignment.center,
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(
                    color: Colors.redAccent,
                    width: 0.5,
                    style: BorderStyle.solid),
              ),
            ),
            padding: const EdgeInsets.only(left: 0.0, right: 10.0),
            child: new Row(
              crossAxisAlignment: CrossAxisAlignment.center,
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                new Expanded(
                  child: TextField(
                    obscureText: true,
                    textAlign: TextAlign.left,
                    decoration: InputDecoration(
                      border: InputBorder.none,
                      hintText: 'samarthagarwal@live.com',
                      hintStyle: TextStyle(color: Colors.grey),
                    ),
                  ),
                ),
              ],
            ),
          ),
          Divider(
            height: 24.0,
          ),
          new Row(
            children: <Widget>[
              new Expanded(
                child: new Padding(
                  padding: const EdgeInsets.only(left: 40.0),
                  child: new Text(
                    "PASSWORD",
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                      color: Colors.redAccent,
                      fontSize: 15.0,
                    ),
                  ),
                ),
              ),
            ],
          ),
          new Container(
            width: MediaQuery.of(context).size.width,
            margin: const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
            alignment: Alignment.center,
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(
                    color: Colors.redAccent,
                    width: 0.5,
                    style: BorderStyle.solid),
              ),
            ),
            padding: const EdgeInsets.only(left: 0.0, right: 10.0),
            child: new Row(
              crossAxisAlignment: CrossAxisAlignment.center,
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                new Expanded(
                  child: TextField(
                    obscureText: true,
                    textAlign: TextAlign.left,
                    decoration: InputDecoration(
                      border: InputBorder.none,
                      hintText: '*********',
                      hintStyle: TextStyle(color: Colors.grey),
                    ),
                  ),
                ),
              ],
            ),
          ),
          Divider(
            height: 24.0,
          ),
          new Row(
            mainAxisAlignment: MainAxisAlignment.end,
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.only(right: 20.0),
                child: new FlatButton(
                  child: new Text(
                    "Forgot Password?",
                    style: TextStyle(
                      fontWeight: FontWeight.bold,
                      color: Colors.redAccent,
                      fontSize: 15.0,
                    ),
                    textAlign: TextAlign.end,
                  ),
                  onPressed: () => {},
                ),
              ),
            ],
          ),
          new Container(
            width: MediaQuery.of(context).size.width,
            margin: const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
            alignment: Alignment.center,
            child: new Row(
              children: <Widget>[
                new Expanded(
                  child: new FlatButton(
                    shape: new RoundedRectangleBorder(
                      borderRadius: new BorderRadius.circular(30.0),
                    ),
                    color: Colors.redAccent,
                    onPressed: () => {},
                    child: new Container(
                      padding: const EdgeInsets.symmetric(
                        vertical: 20.0,
                        horizontal: 20.0,
                      ),
                      child: new Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: <Widget>[
                          new Expanded(
                            child: Text(
                              "LOGIN",
                              textAlign: TextAlign.center,
                              style: TextStyle(
                                  color: Colors.white,
                                  fontWeight: FontWeight.bold),
                            ),
                          ),
                        ],
                      ),
                    ),
                  ),
                ),
              ],
            ),
          ),
          new Container(
            width: MediaQuery.of(context).size.width,
            margin: const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
            alignment: Alignment.center,
            child: Row(
              children: <Widget>[
                new Expanded(
                  child: new Container(
                    margin: EdgeInsets.all(8.0),
                    decoration: BoxDecoration(border: Border.all(width: 0.25)),
                  ),
                ),
                Text(
                  "OR CONNECT WITH",
                  style: TextStyle(
                    color: Colors.grey,
                    fontWeight: FontWeight.bold,
                  ),
                ),
                new Expanded(
                  child: new Container(
                    margin: EdgeInsets.all(8.0),
                    decoration: BoxDecoration(border: Border.all(width: 0.25)),
                  ),
                ),
              ],
            ),
          ),
          new Container(
            width: MediaQuery.of(context).size.width,
            margin: const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
            child: new Row(
              children: <Widget>[
                new Expanded(
                  child: new Container(
                    margin: EdgeInsets.only(right: 8.0),
                    alignment: Alignment.center,
                    child: new Row(
                      children: <Widget>[
                        new Expanded(
                          child: new FlatButton(
                            shape: new RoundedRectangleBorder(
                              borderRadius: new BorderRadius.circular(30.0),
                            ),
                            color: Color(0Xff3B5998),
                            onPressed: () => {},
                            child: new Container(
                              child: new Row(
                                mainAxisAlignment: MainAxisAlignment.center,
                                children: <Widget>[
                                  new Expanded(
                                    child: new FlatButton(
                                      padding: EdgeInsets.only(
                                        top: 20.0,
                                        bottom: 20.0,
                                      ),
                                      child: new Row(
                                        mainAxisAlignment:
                                        MainAxisAlignment.spaceEvenly,
                                        children: <Widget>[
                                          Icon(
                                            const IconData(0xea90,
                                                fontFamily: 'icomoon'),
                                            color: Colors.white,
                                            size: 15.0,
                                          ),
                                          Text(
                                            "FACEBOOK",
                                            textAlign: TextAlign.center,
                                            style: TextStyle(
                                                color: Colors.white,
                                                fontWeight: FontWeight.bold),
                                          ),
                                        ],
                                      ),
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
                new Expanded(
                  child: new Container(
                    margin: EdgeInsets.only(left: 8.0),
                    alignment: Alignment.center,
                    child: new Row(
                      children: <Widget>[
                        new Expanded(
                          child: new FlatButton(
                            shape: new RoundedRectangleBorder(
                              borderRadius: new BorderRadius.circular(30.0),
                            ),
                            color: Color(0Xffdb3236),
                            onPressed: () => {},
                            child: new Container(
                              child: new Row(
                                mainAxisAlignment: MainAxisAlignment.center,
                                children: <Widget>[
                                  new Expanded(
                                    child: new FlatButton(
                                      padding: EdgeInsets.only(
                                        top: 20.0,
                                        bottom: 20.0,
                                      ),
                                      child: new Row(
                                        mainAxisAlignment:
                                        MainAxisAlignment.spaceEvenly,
                                        children: <Widget>[
                                          Icon(
                                            const IconData(0xea88,
                                                fontFamily: 'icomoon'),
                                            color: Colors.white,
                                            size: 15.0,
                                          ),
                                          Text(
                                            "GOOGLE",
                                            textAlign: TextAlign.center,
                                            style: TextStyle(
                                                color: Colors.white,
                                                fontWeight: FontWeight.bold),
                                          ),
                                        ],
                                      ),
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                ),
              ],
            ),
          )
        ],
      ),
    );
  }

有人知道如何解决吗？