内部的IE7换行会扰乱底部边缘

I noticed strange behavior in IE7 that does not occur in Firefox. If you notice in "testing 2" "div",when I add 2 line breaks at the bottom of this div, it does not respect margin set up for this div, and "test 3" div is right below it without margins. When I remove "br" then "test 2" and "test 3" divs have margins between them.I noticed strange behavior in IE7 that does not