The Expandable Fields Snippet demonstrates how a text field expands to accommodate multiple lines of data. In this example, five question fields must adjust to accommodate more than one line of text.
For each Text Field object, you specify that the text fields can accept one or more lines of wrapping text by selecting the Allow Multiple Lines option in the Field tab of the Object palette.
Livecycle expandablefields Allowing multiple lines of text in text fields
See also 

Allowing multiple lines of text in text fields