Simple HTML trick to get this :
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" rel="stylesheet"/>_x000D_
<div class="row" >_x000D_
_x000D_
<div class="col-md-6">_x000D_
<div class="row">_x000D_
<div class="col-md-4" >_x000D_
<label for="hours">Hours</label>_x000D_
<select class="form-control" required>_x000D_
<option> </option>_x000D_
<option value="1"> 1 </option>_x000D_
<option value="2"> 2 </option>_x000D_
<option value="3"> 3 </option>_x000D_
<option value="4"> 4 </option>_x000D_
<option value="5"> 5 </option>_x000D_
<option value="6"> 6 </option>_x000D_
<option value="7"> 7 </option>_x000D_
<option value="8"> 8 </option>_x000D_
<option value="9"> 9 </option>_x000D_
<option value="10"> 10 </option>_x000D_
<option value="11"> 11 </option>_x000D_
<option value="12"> 12 </option>_x000D_
</select>_x000D_
</div>_x000D_
<div class="col-md-4" >_x000D_
<label for="minutes">Minutes</label>_x000D_
<select class="form-control" required="">_x000D_
<option selected disabled> </option>_x000D_
<option value="00"> 00 </option>_x000D_
<option value="10"> 10 </option>_x000D_
<option value="20"> 20 </option>_x000D_
<option value="30"> 30 </option>_x000D_
<option value="40"> 40 </option>_x000D_
<option value="50"> 50 </option>_x000D_
</select>_x000D_
</div>_x000D_
<div class="col-md-4" >_x000D_
<label for="hours">Select Meridiem</label>_x000D_
<select class="form-control" required="" >_x000D_
<option selected="" value="AM"> AM </option>_x000D_
<option value="PM"> PM </option>_x000D_
</select>_x000D_
</div>_x000D_
</div></div>_x000D_
</div>
_x000D_