.org/reference/geom_histogram.html" class="external-link">geom_histogram</a></span><span class="op">(</span>position <span class="op">=</span> <span class="st">"identity"</span>, alpha <span class="op">=</span> <span class="fl">.5</span><span class="op">)</span> <span class="op">+</span></span>
<span>  <span class="fu"><a href="https://ggplot2.tidyverse.org/reference/labs.html" class="external-link">labs</a></span><span class="op">(</span>x <span class="op">=</span> <span class="st">"面積（a）"</span>,<