if a request or advice falls on deaf ears, people ignore it.

Appeals to release the hostages fell on deaf ears.

Warnings that sunbathing can lead to skin cancer have largely fallen on deaf ears in Britain.

• knock the living daylights out of
• knock the living daylights out of someone
• knock them dead
• knock the stuffing out of
• knock the stuffing out of someone
• knock the tar out of
• knock the tar out of someone
• knock up
• knock wood
• knock yourself out
• knock your socks off
• know-all
• know a thing or two
• know backwards
• know backwards and forwards
• know beans about
• know beans about something
• know best
• know better
• know better than to
• know better than to do something
• know by heart
• know by sight
• know different
• know from Adam