问为什么我的模式不会出现在React Bootstrap的屏幕上？

EN

import React from 'react';
import { Button, ButtonToolbar, Modal } from 'react-bootstrap';
class LoginPage extends React.Component {
    constructor(props, context) {
      super(props, context);

      this.handleShow = this.handleShow.bind(this);
      this.handleClose = this.handleClose.bind(this);

      this.state = {
        show: false,
      };
    }

    handleClose() {
      this.setState({ show: false });
    }

    handleShow() {
      this.setState({ show: true });
    }

    render() {
      return (
        <div>
        <p>Click to get the full Modal experience!</p>
        <Button bsStyle="primary" bsSize="large" onClick={this.handleShow}>
          Launch demo modal
        </Button>

        <Modal show={this.state.show} onHide={this.handleClose}>
          <Modal.Header closeButton>
            <Modal.Title>Modal heading</Modal.Title>
          </Modal.Header>
          <Modal.Body>
            <h4>Text in a modal</h4>
            <p>
              Duis mollis, est non commodo luctus, nisi erat porttitor ligula.
            </p>
          </Modal.Body>
          <Modal.Footer>
            <Button onClick={this.handleClose}>Close</Button>
          </Modal.Footer>
        </Modal>
      </div>
      );
    }
  }

export default LoginPage;