영어고수님들설명좀 부탁드립니다^^

다음예문들이 왜~ 올바른문장이고 틀린문장인지 분석들좀.........ㅜ!!

1. this book is worth reading ( o )

2. this book is worth to read ( x )

3. this book is worth while reading ( x )

4. this book is worth while to read ( o )

5. it is worth reading this book ( x )

6. it is worth to read this book ( x )

7. it is worth while reading this book ( o )

8. it is worth while to read this book ( o )

1.2.3.4 번은 기본문장이니 이해가가는데 5번부터는..... it을 가주어로 쓴거같은데 왜 틀리고 맞는지를!!!!! 좀알려주실분!

부탁드릴게요^^