[Idiom] Idiom: "Up in the air"- Is it a formal?

[shanghailuv]

I could not find any specific and solid info which says if the idiom "up in the air" is formal. I am afraid that I will be scored down if I use it in my essay, in case it is an informal idiom and not a good fit for academic essays.

Please advise.

 

[Gillnetter]

I could not find any specific and solid info which says if the idiom "up in the air" is formal. I am afraid that I will be scored down if I use it in my essay, in case it is an informal idiom and not a good fit for academic essays.

Please advise.

i wouldn't use it in a formal paper. Something like "unclear", "as yet not decided", or "open to question" might be better.

 

[shanghailuv]

In the same context of idioms being formal or informal, what about the idiom - "Bend over backwards"?

 

[Rover_KE]

Definitely informal.