[Plugin: Contact Form 7] Next row – checkboxes

I have got contatc form 7 and i am using Checkboxes. When I add choices, all of chopises are in one row but I want add one choice at one row.

For example: [checkbox* uroven use_label_element “začiatočník” “mierne pokročilý” “pokročilý”]

Thanx

http://ww.wp.xz.cn/extend/plugins/contact-form-7/