title: How to make cardview show only bottom shadow
body: <p>i use following code:</p>
  
  <pre><code>&lt;android.support.v7.widget.CardView
          xmlns:app="http://schemas.android.com/apk/res-auto"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          app:cardUseCompatPadding="true"
          app:cardElevation="4dp"&gt;
      &lt;TextView android:text="in card view" android:layout_width="match_parent" android:layout_height="wrap_content"/&gt;
  &lt;/android.support.v7.widget.CardView&gt;
  </code></pre>
  
  <p>the screenshot is:</p>
  
  <p><a href="https://i.stack.imgur.com/kaTet.png" rel="noreferrer"><img src="https://i.stack.imgur.com/kaTet.png" alt="enter image description here"></a></p>
  
  <p>how to make only bottom show shadow?</p>