1, I usually stayed up late to watch football matches last year, but now I don't
=> I used to stay up late to watch football matches
2, There were some trees in the field, but now there aren't any 
=> There used to be some trees in the field
3, Tam doesn't type as fast as she used to 
=>Tam used to type fast
4, They will show the time machine to the public when they finish it 
=> The time machine will be shown to the public when they finish it 
Nhớ tặng điểm cho mình nha ^^