ˌcave ˈin (on sb/sth)
(of a roof, wall, etc. 房顶、墙等) to fall down and towards the centre 塌落；塌陷；坍塌
The ceiling suddenly caved in on top of them.
他们头顶的天花板突然塌落。
related noun cave-in
ˌcave ˈin (to sth)
to finally do what sb wants after you have been strongly opposing them 让步；屈服；屈从
The President is unlikely to cave in to demands for a public inquiry.
总统未必会同意进行公开调查。