Rewrite senteces, using the provided word keep meaning as that of the root one

I. Rewrite senteces , using the provided word keep meaning as that of the root one
1. Knowing English is very useful
--->It
2.It started to snow at 5 o'clock
--->It
3.What time does Nam have to leave?
---->Do you know
4.To do morning exercises is good
---->It
5. This book is very boring and so is that one
--->This book is as
6.Will it be necessary for me to sleep under a net
--->Shall i
7.I last read a book on September 20th
--->T haven't
8. An began to be interested in healthy eating 3 years ago
----> An has been