用it改写下面句子

题目

用it改写下面句子
(5) I am very pleased to hear that you have learned computer.
(6) You don't need to worry.It's really unnecessary.
(7) Tom repaired the printer.That was very clear.
(8) To buy this old kind of computer is no longer possible.

答案

(5)It is pleasant to hear...
(6)It is really unnecessary to worry.
(7)It is very clear that Tom repaired the computer.
(8)It is no longer possible to...