Rewrite the following sentences:
1.Knowing English is very useful - It...........................................................................................................
2.Nam is taller than Hung - Hung.................................................................................................................
3.To do morning exercises is good - It.........................................................................................................
4.This book is very boring and so is that one - This book is as...................................................................
5. It is not as warm in Canada as it is in Mexico - Mexico...........................................................................
6. The sun is much hotter than the moon - The moon isn't...........................................................................
7. You can't understand these things because you are very young - You are not.........................................
8. This shirt is too dirty for me to wear - This shirt.....................................................................................