〜のではないか / 〜のではないだろうか (no dewa nai ka / no dewa nai darou ka)

Kono keikaku wa sukoshi muri ga aru no dewa nai darou ka.

Isn't this plan a bit unreasonable?

Kare no setsumei wa, sukoshi kotoba ga tarinai no dewa nai darou ka.

Isn't his explanation a bit lacking in words?

Saikin no wakamono wa, sumātofon no tsukaisugi na no dewa nai darou ka.

Aren't young people these days using their smartphones too much?

Kono shōhin no kakaku wa, takasugiru no dewa nai ka to omoimasu.

I think the price of this product might be too high.

Mō ichido, zen'in de hanashiatte kimeru beki na no dewa nai deshō ka.

Shouldn't we discuss it again with everyone before making a decision?

Mainichi osoku made hataraku no wa, karada ni yokunai no dewa nai darou ka.

Isn't it bad for your health to work late every day?