Is there a way to concatenate multilines in [onshow; if [var.x]!='0'; then ' multilines here ';else '']

Question

How to concatenate multiline string in [onshow if then else] condition with tbs variables? Thanks for your help.

I work on windows 10 + WAMP.
I had try the code bellow. I suppose the problem is coming from the tbs variables incuded in. I did'nt find the way to eliminate this error:

"
TinyButStrong Error : can't found the end of the tag '[onshow; if [var.x...'.

TinyButStrong Error : can't found the end of the tag '[onshow; if [var.x...'.

TinyButStrong Error : can't found the end of the tag '[onshow; if 0!='0'...'.

TinyButStrong Error : can't found the end of the tag '[onshow; if 0!='0'...'.
"

[onshow; if [var.x_created_dupli]!='0'; then '<td>
    <select name="x_exercise" size="10" onchange="chooseExercise();">
    <option value="[blk_exercise.key]">[blk_exercise.val;block=option;strconv=utf8]'</option>
    <option>[onshow.x_exercise;ope=html;select]</option>
    </select>
</td>
<td>
    <input type="button" name="action" value="ajouter exercice" onclick="alterExercise([onshow.x_sessionType],2)"/>
</td>';else '']