how sat drop down list in bootstrap 4 like a row and column
<div class="form-row"> <div class="form-group col-2"> </div> <div class="form-group col-5"> </div> <div class="form-group col-5"> </div> </div> <div clas="form-row"> <div class="form-group col-4"> </div> <div class="form-group col-4"> </div> <div class="form-group col-4"> </div> </div>