1.The exercise is very difficult. We can't do it.
->The exercise is too difficult for us to do
2.We usually get up early.
->We are not used to getting up late
3.We have never seen this film before.
->This is the first time I've seen this film
4.She doesn't know how to play the game.
->She wishes she knew how to play the game
5.Nobody can find the solution.
->The solution can't be found.
6.She is too old to drive the car.
->She isn't young enough to drive a car
7.I haven't heard from them since 1990.
->They haven't been heard since 1990
8.I haven't played tennis for 4 years.
->I last played tennis 4 years ago
9.I don't live in Hue now.
->I used to live in Hue
10.We started learning to ride 10 years ago.
->We have learnt to ride for 10 years
11.This is the first time i have been to Thailand.
->I haven't been to Thailand before
12.They're still at work.
->They haven't relaxed
14.I can't go to the party with you next week.
->I wish I could go to the party with you next week
15.They're excited about meeting you.
->They're looking forward to meeting you soon
16.He isn't strong enough to carry the sofa.
->He wishes he were strong enough to carry the sofa
17.Let's go to the cinema tonight.
->Why don't we go to the cinema tonight
18.This is the best hotel.
->There isn't any hotel better than this one
19.During my bath, i heard a terrible noise.
->While I was having bath, I heard a terrible noise
20.We have run out of sugar.
->There isn't any sugar left