如何创建33% / 33% / 33% / 100% / 100%的flexbox布局？

.container {
  display: flex;
}

<div class="container">
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
  <div class="box"></div>
</div>

.box:nth-child(1),
.box:nth-child(2),
.box:nth-child(3) {
  flex-basis: 33%;
}

.box:nth-child(4),
.box:nth-child(5) {
  flex-basis: 100%;
}

.box {
  background-color: #ccc;
  border: 1px solid #000;
}