Bootstrap 4导航栏删除下拉菜单项上的悬停

Question

我正在迁移到Bootstrap 4，目前正在修复导航栏。问题是，当我用鼠标悬停在下拉菜单上时，它们会打开。

我需要删除当用户将鼠标悬停在上方时打开的下拉菜单。我遵循了官方引导网站上的示例，因此，我不理解，悬停选项是默认启用还是其他功能？

@helper GenerateMenuItem(MenuItem menu_item)
{
    if (!(menu_item.SubMenus.Where(it => it.AllowedRoles.Any(role => User.IsInRole(role))).Count() == 0 && menu_item.Url == null))
    {
        <li class="nav-item dropdown px-1">
            @if (menu_item.SubMenus.Where(it => it.AllowedRoles.Any(role => User.IsInRole(role))).Count() > 0)
            {
                <a class="nav-link dropdown-toggle @menu_item.IconClass" aria-expanded="false" id="navbarDropdownMenuLink" href="@(menu_item.GetFullUrl() == null ? "javascript:" : menu_item.GetFullUrl())">@menu_item.DisplayText <span class="fa fa-caret-down"></span></a>
                <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                    @foreach (MenuItem submenu_item in menu_item.SubMenus.Where(it => !it.ToSort && it.AllowedRoles.Any(role => User.IsInRole(role))))
                    {
                        @GenerateMenuItem(submenu_item)
                    }
                    @foreach (MenuItem submenu_item in menu_item.SubMenus.Where(it => it.ToSort && it.AllowedRoles.Any(role => User.IsInRole(role))).OrderBy(it => it.DisplayText))
                    {
                        @GenerateMenuItem(submenu_item)
                    }
                </ul>
            }
            else
            {
                if (menu_item.GetFullUrl() == null)
                {
                    <a>@menu_item.DisplayText</a>
                }
                else
                {
                    <a class="dropdown-item" href="@(menu_item.GetFullUrl() == null ? "javascript:" :  menu_item.GetFullUrl())">@menu_item.DisplayText</a>
                }
            }
        </li>
    }
}