1.The ladder is too short to reach the window
⇒The ladder isn't long enough to reach the window.
2.Riding a bicycle so fast is dangerous
⇒It's dangerous to ride a bicycle so fast.
3.When I was small my family lived in Hai Phong
⇒My family used to live in Hai Phong when I was small.
4.They won't be able to come on Sunday
⇒It will be impossible for them to come on Sunday