Dampen down
to make something such as a feeling or hope less strong (किसी चीज को कमजोर बनाना)
Nothing should be done to dampen down his ardent enthusiasm.
Fall down on
be shown to be inadequate or unsuccessful; fail (किसी चीज को सफल करने में फेल हो जाना)
You should not fall down on your promise.
Fall in
to go down quickly into (something) (किसी का ढह जाना/ गिर जाना)
The roof of my house fell in yesterday.
Fall in with
meet someone by chance and become involved with them. (किसी से संयोग से मिलना और उनके साथ शामिल हो जाना)
He fell in with thieves.