on alert
on guard
It is stupid to tolerate "Nikola;" all Chekists have to be on alert to shoot anyone who doesn't turn up to work because of "Nikola." Vladimir Lenin
Every time I think I have something under control, it changes and I don't have it under control. I think it takes several years to get there. Jade is 19 months old, so right now I'm on alert all the time. And as a mom I think you're constantly worrying about things. Giada De Laurentiis
Octopus can fish for prey while deciding what color and pattern to turn, what shape to make their bodies, be on alert for predators and aware how far away their dens are. Sy Montgomery