collapse, collapses, collapsing, collapsed, to crumble, crumble, crumbles, crumbling, crumbled
Mnemonic
[b-] Bart Simpson is in [1] front of the [-(e)ng] English manor where there is a small 山 mountain. He gets two small 月 moons and puts them in each hand and starts beating the 山 mountain with them. The 山 mountain slowly starts 崩 to collapse, as the rich kids behind him stare with bewilderment. What is his endgame?