n><span class="st">"Emissions"</span>,<span class="st">"Certificate"</span>,<span class="cn">NA</span>,</span>
<span>                       <span class="cn">NA</span>,<span class="st">"TRUE"</span>,<span class="st">"FALSE"</span>,<span class="st">"TRUE"</span>,<span class="st">"TRUE"</span><span class="op">)</span></span>
<span><span class="op">)</span></span>
<span><span class="va">vehicles_skip</span></span>
<span><span class="co">#&gt;           X1               X2    X3          X4</span></span>
<span><