How can I allow my users to preview their responses before submitting the form?

i am sorry ,my english not good ,

my means is if a user post a form,i want to let he can preview his post content and send the post,if he find has some mistake ,he can go back to revise his post and send the post 

thank you

Yes, this is possible. You just need to add the preview before submit widget to your form in order to accomplish this.

You can see here: http://form.jotformpro.com/form/50262970513956 a demo form with the widget in it so you can see how it works.

Let us know if this helps.