Bootstrap 4 如何创建引导4水平子菜单？

我正在创建acedemics下拉菜单，它可以正常工作，但我需要syallbus的水平两个子菜单1）D.Farm syallbus 2）B.Pharm syallbus plz需要帮助

 <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          ACEDEMICS
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">SYLLABUS</a>
          <a class="dropdown-item" href="#">FACULTY</a>
          <a class="dropdown-item" href="#">RULES & REGULATIONS</a>
        </div>
      </li>