引导程序导航栏列表项目出现在一行上

Question

<div class="container">
    <div class="row">
        <nav class="navbar navbar-inverse  navbar-right"> <a href="#" class="navbar-brand">Expand</a>
            <div class="d-flex justify-content-end">
                <ul class="navbar-nav">
                    <li class="nav-item"><a href="#" class="nav-link">Overview</a></li>
                    <li class="nav-item"><a href="#" class="nav-link">Specs</a></li>
                    <li class="nav-item"><a href="#" class="nav-link">FAQ</a></li>
                    <li class="nav-item"><a href="#" class="nav-link">Purchase</a></li>
                </ul>
            </div>
        </nav>
    </div>
</div>

此处列表项一个接一个地出现，如何使它们出现在一行