Question

when a concave mirror forms an image of nature virtual and erect ?

Answer 1

when the object is placed between pole and focus then in that case concave mirror gives virtual and erect image of an object

Answer 2

When the object is closer to the mirror than the focal point, the image formed will be upright, enlarged, and virtual.
 example is the small mirror typically used by dentists and dental hygienists to look at details of your teeth.