1.TO learn computer is useful.
-> It is useful to learn computer.
2 .They look down on the poor,they are not right.
-> It is not right for them to look down on the poor.
3 .The boy doesn"t shout to the ole man.he is polite.
-> It is polite of the boy not to shout to the old man.
4.It"s patient of you to wait for two hours here.
-> You have waited here for two hours.You are patient.
5.The boy is very strong .he can lift the box
-> The boy is strong enough to lift the box.