These are phrases for now. Unfinished sentences! However, you can make them sentences, if you add a subject, among other things. "(He let out a) cry of laughter." "(She'll) cry with laughter (if you tell her that joke)." "Mourn" means to show sorrow and regret, so "laughter" (being happy) does not fit next to "mourn". You mourn at a funeral, you mourn when you lose someone you love. Hope this helps!

these are not sentences...