Space between two phrases

[Hyeonah]

Hello!
I was wondering whether I could make some space between two phrases. 
For instance, I want to create a stimulus that shows "a key                 to lock". 
However, when I made some space manually between the two phrases using a spacebar and run a preview, the two phrases were adjacent without any separation.
So instead, I used dashes and this is how I coded for this stimulus:
{

  "type": "text",
  "content": "a key----------------------------------to lock",
  "alignment": "left",
  "size": "50px"
}


However, I'd like to know whether there is a way to make some space between the two phrases without using dashes. 

Thanks!