洞穴探险是一项需要专业装备的冒险活动。

___Caving is an adventurous activity that requires specialized equipment.

旧矿道的顶部正在坍塌，非常危险。

The ceiling of the old mine tunnel is ___caving in, which is very dangerous.

在父母的不断劝说下，他最终妥协了。

Under his parents' persistent persuasion, he finally ___caved in.