If there is a question where most people probably will fill in the same answer, you can see to that that answer already is in the field by default. E.g. What country do you come from? You can fill in current country and if the participant wants to change the answer it is only to write your own and delete the old answer.
Here you can valdiate the input field, i.e. see to that the right things are filled in by using regular expressions, or see to that an e-mail adress really is an email-address. Read more about regular expressions: