Please read the following table in HTML format from a webpage and then answer the question in detail according to the table. Each table cell is defined by a <td> and a </td> tag. Each table row starts with a <tr> and ends with a </tr> tag. 'rowspan=m' and 'colspan=n' represents a cell spaning over 'm' rows and 'n' columns.

Webpage title:
Messerschmitt Bf 109 in Yugoslav service
Table title:
Royal Yugoslav Air Force
Table:
<table id='hittask' contenteditable='False'>
<tr> <th colspan=1 rowspan=1 > Formation </th><th colspan=1 rowspan=1 > Unit </th><th colspan=1 rowspan=1 > Location </th><th colspan=1 rowspan=1 > Aircraft </th><th colspan=1 rowspan=1 > Notes </th></tr>
<tr> <td colspan=1 rowspan=1 > 1st Fighter Brigade </td><td colspan=1 rowspan=1 > 702nd Liaison Squadron </td><td colspan=1 rowspan=1 > Zemun </td><td colspan=1 rowspan=1 > 2 </td><td colspan=1 rowspan=1 > — </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 2nd Fighter Regiment </td><td class="highlighted"  colspan=1 rowspan=1 > 31st Fighter Group </td><td class="highlighted"  colspan=1 rowspan=1 > Knić </td><td colspan=1 rowspan=1 > 19 </td><td colspan=1 rowspan=1 > 101st and 141st Squadrons </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=2 > 6th Fighter Regiment </td><td class="highlighted"  colspan=1 rowspan=1 > 32nd Fighter Group </td><td class="highlighted"  colspan=1 rowspan=1 > Prnjavor </td><td colspan=1 rowspan=1 > 27–28 </td><td colspan=1 rowspan=1 > 103rd, 104th and 142nd Squadrons </td></tr>
<tr> <td class="highlighted"  colspan=1 rowspan=1 > 51st Fighter Group </td><td class="highlighted"  colspan=1 rowspan=1 > Zemun </td><td colspan=1 rowspan=1 > 10 </td><td colspan=1 rowspan=1 > 102nd Squadron </td></tr>
<tr> <td colspan=1 rowspan=1 > — </td><td colspan=1 rowspan=1 > 81st Bomber Group </td><td colspan=1 rowspan=1 > Mostar </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=1 > Independent Fighter Squadron </td></tr>
<tr> <td colspan=1 rowspan=1 > — </td><td colspan=1 rowspan=1 > Air Training School </td><td colspan=1 rowspan=1 > Mostar </td><td colspan=1 rowspan=1 > 3 </td><td colspan=1 rowspan=1 > — </td></tr>
</table>
Question:
Which Fighter Groups used the Bf 109 and where were they posted?
Answer:
The Bf 109 was used to equip the 31st Fighter Group of the 2nd Fighter Regiment at Knić, and the 32nd and 51st Fighter Groups of the 6th Fighter Regiment at Prnjavor and Zemun.