1. To make you agree with me is disapointing (it.....)
=> It is disapointing to make you agree with me
2. It isn't easy to keep in touch with his mother (to.....)
=> It isn't easy to keep in touch with his mother
3. Nga started to keep this dog 4 years ago (for)
=> For 4 years, Nga has started to keep this dog.
4. You are interested in protecting the environment. We are delighted (that)
=> We are delighted that you are interested in protecting the environment
5. Are you certain ? Your brother will help us with the problems (that)
=> Are you certain that your brother will help us with the problems?
6. He drank a lot of black coffe. He wants to keep awake(so as to)
=> so as to keep awake, he drank a lot of black coffe.