Css 为什么这些列是垂直堆叠而不是水平引导4

我最近升级到Bootstrap4，并注意到我的图库在Bootstrap3上很好（水平列出），现在突然垂直堆叠起来

为什么呢？什么改变了

我的专栏：

<div class="row gallerymargin">
    <div class="col-md-12">
        <div class="latest_posts default-style">
            <div class="row" id="contentgallery">
                  <div id="album">
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/8200trouwen.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/8200trouwen.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/Job.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/Job.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/bouwenmet5000.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/bouwenmet5000.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/eersteloodssloophooiberg.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/eersteloodssloophooiberg.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/geschiedenis2.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/geschiedenis2.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                    <div class="col-sm-6 col-lg-4 post">
                      <a href="cms/images/gallerijen/over-ons/geschiedenis3.jpg" target="_blank" class="hoverBorder plus lightgallerytrigger">
                        <span class="hoverBorderWrapper">
                          <img style="object-fit:cover;width:100%;height:200px;" src="cms/images/gallerijen/over-ons/geschiedenis3.jpg" class="img-responsive" width="370" height="200" alt="" title="">
                          <span class="theHoverBorder"></span>
                        </span>
                        <h6>Bekijk foto +</h6>
                      </a>
                    </div>
                </div>
            </div>
            <!--/ row -->
        </div>
    </div>
</div>

我网站上的所有其他元素都很好，所以我很难弄清楚是什么导致了这一现象

从HTML代码中删除此div

由于

bootstrap4

使用

Flex布局

，因此应将Flex属性赋予其直接子级（此处为相册类）

从HTML代码中删除此div

---

由于

bootstrap4

使用

Flex布局

，Flex属性应该被赋予它的直接子级（这里是album类）

img responsive

类被重命名为

img流体

btw

col

必须是

行

img responsive

类被重命名为

img流体

btw

col

必须是

行

的直系子类。谢谢，这起作用了。你知道为什么从现在起它会这样吗？行需要直接位于列的上方？您应该解释为什么这会有帮助。@t是的，在

行

下只能存在一个

列，即：在网格布局中，内容必须放在列中，只有列可以是行的直接子行谢谢，这很有效。你知道为什么从现在起它会这样吗？行需要直接位于列的上方？您应该解释为什么这会有帮助。@t是的，在
行
下只能存在一个
列，即：在网格布局中，内容必须放在列中，只有列可以是行的直接子项