我尽量板着面孔，但最后还是控制不住失声大笑起来。

I kept a straight face as long as I could, but I finally had to crack up.

阵阵哈哈大笑声

раскаты хохота

大声笑个不停

laugh loud and long

不停的哈哈大笑声

несмолкаемый хохот

我们忍不住大声笑了起来

мы не утерпели и громко засмеялись

她的情绪变化无常，一会儿放声大笑，一会儿陷于绝望。

Her moods were very changeable, now laughing loudly, and now sunk in despair.