I have a problem about text on path. The bottom of the letters is in the middle of the path. I want the middle of the letters to be in the middle of the path. Is there any method to solve this?

Depends on your needs. You can simply duplicate the blue path and give a thinner white stroke to it on top, or use the dynamic offsetting option on duplicants, convert it back to paths and remove unwanted segment if necessary (as it produces closed paths only.) Other solution would be to add a patt...

Is there a way to draw parallel paths like this?