1.使用display:table和display:table-cell

<div class="parent">
  <p class="son">我要占C位！！！ </p>
</div>

.parent {
  display: table;
  width: 300px;
  height: 300px;
  text-align: center;
}
.son  {
  display: table-cell;
  height: 200px;
  background-color: yellow;
  vertical-align: middle;
}
···