Question

1. This book is really fun.
2. This book is real fun.
3. This book is great fun.

(Which one is correct? Are all corect? What is the part of speech of 'fun'?)

4. Shine a light on the back of the stage.

5. Shine a light at the back of the stage.

6. Shine a light in the back of the stage.

(Are all the same and grammatical? Do they have differences?)

Answer 1

1 and 3 are fine; 2 is not grammatically correct.
"Fun" is a noun.
http://www.answers.com/topic/fun

4, 5, 6 -- I've answered these before.

Answer 2

1. This uses the adverb "really"
2. This uses the adjective "real" and is not good.
3. OK and fun is a noun

4. the light has to be above

5. the light is somewhere toward the back

6. the light could be anywhere

4, 5, 6 are all fine grammatically but there "could" be differences.

Sra