Use a superlative :
Example : "This exercise is very difficult : it's the most difficult exercise" (I've ever done !)
1- It was a very happy day : it was ................in my life.
2- It's a very good book : it is................... I've ever read.
3- He's a very famous singer : he's certainly............................. in the country.
4- I know it was a bad mistake : it was ..........................I had ever done.
5- She's a very pretty : she's ...........................of the class.
6- It was a very cold winter : it was .............................we had ever known.
7- Jack is a boring man : he's ........................I've ever met.
8- Alice is really a funny child : she is ............................in the family.