Cannot afford to / Not possible to
This expression is used to indicate that one cannot do something due to a situation or condition.
Examples
ここで泣くわけにはいかない。
I can't afford to cry here.
仕事中に寝るわけにはいかない。
I can't sleep while working.
試験の前に休むわけにはいかない。
I can't rest before the exam.
Quick check
I can't sleep while working. 仕事中に寝る___。