Fill in the blanks:

(a) An image that cannot be obtained on a screen is called ___________ .

(b) Image formed by a convex is __________ always virtual and smaller in size.

(c) An image formed by a __________ mirror is always of the same size as that of the object.

(d) An image which can be obtained on a screen is called a __________ image.

(e) An image formed by a concave __________ cannot be obtained on a screen.