如何在表<th>中显示可见的下拉菜单

Question

我试图在表格中实现下拉菜单，但是下拉菜单隐藏在其后面，并且不显示如何在表格中显示下拉菜单，我也在这里插入了我可以看到的代码，我还将添加错误图像尝试visible !important1无效

1. 否                车牌号

              {/* For Type Th */}
              <th>
                <span
                  id="dropdownMenuLink"
                  role="button"
                  className="dropdown-toggle"
                  data-toggle="dropdown"
                  aria-haspopup="true"
                  aria-expanded="false"
                  //
                >
                  Type
                </span>
                <div
                  class="dropdown-menu nott "
                  aria-labelledby="dropdownMenuLink"
                  style={{ position: "relative", zIndex: "9999999" }}
                >
                  <a class="dropdown-item" href="# ">
                    Action
                  </a>
                  <a class="dropdown-item" href="/dashboard ">
                    dashboard
                  </a>
                  <a class="dropdown-item" href="# ">
                    Something else here
                  </a>
                </div>
              </th>
              <th>Mileage[km]</th>