Thanks all for your prompt answers
Yes I add a string parameter and it was fine when I set its MultiValue property as No.
I wanted a big text area so I set MultiValue property as Yes. At this time I got a big area but I wasn't able to add text.
Do I can write in this area with MultiValue property = Yes
When I used SQL expression parameter and another parameter as Feature class or Feature layer, The Obtained from property of the SQL expression parameter was not reachable, meaning that I was not able to link this parameter to the layer
Any help please?
Thanks