The signs "school, kindergarten, nursery school, etc. ahead," "left curve ahead," and "right curve ahead" are all classified as warning signs.

Answer: True

Explanation

According to the Rules of the Road, warning signs give advance notice to road users of hazards or situations requiring attention on the road and call for caution. Locations with schools, kindergartens, nursery schools, etc., and places where the road curves left or right present hazards such as children dashing out or accidents on curves, so advance notice through warning signs is necessary.