Up in the air
If something, such as a plan or a decision, is up in the air, it has not been decided or settled yet
Example: I can’t give you a definite answer yet; the project is still up in the air
Ugly as sin
This expression is used to refer to people or things that are considered to be very unattractive
Example: Have you seen the new neighbor’s dog? It’s as ugly as sin
Under your thumb
If someone is under your thumb, they are completely under your control or influence
Example: Nobody ever protests. He has the whole group under his thumb
Voice in the wilderness
If you are the only person expressing a warning or an opinion on a matter which is ignored by most others, you are a voice in the wilderness
Example: For many years she was a voice in the wilderness protesting against child labor
Vote with one’s feet
If you vote with your feet, you show your dislike or disapproval of something by leaving
Example: If the conference is boring, people will probably vote with their feet
Vanish into thin air
If something vanishes into thin air, it disappears completely in a mysterious way
Example: The diamonds vanished into thin air – nobody knows what happened to them