1.She has worn that dress at her sister's wedding.

2.It is such a tidy room that it takes us one hour to clean

3.It was such a warm news that they had a walk in the garden.

4.The blue shirt is not as expensive as the red one

5.Elizabeth doesn't play the piano as well as Jane.

6.If I knew her address, I would tell you.

1.She began to wear that dress at her sister's wedding 
-> she has begun to wear that dress at her sister wedding
-> she has been wearing that dress since her sister’s wedding 
2.The room is so tidy that is took us one hour to  clean it 
-> It is such a clean room that we cleaned us for one hour
3. The news was so warm that they had a walk in the garden 
-> it was such a warm news that they had a walk in the garden
4.the red shirt is more expensive than the blue one 
->the blue shirt isn't as expensive as the red shirt
-> the blue shirt is cheaper than the red one
5. Jane plays the piano better than Elizabeth 
-> Elizabeth doesn't play the piano as well as Jane
6.I don't know her address, so I can't tell you 
->If I knew her address, I would tell you.