what does "you can or cannot?

[andrewwai]

watch the traffic when you cross the street -you can't be too careful or you can't be too careless to mean 'you must be careful?

[pinus]

If I understand your question correctly: "You can't be too careful" In other words, take care, and then take more care Check once, check twice, check again. Look right, Look left, Look right again, and keep watching.