1. I find it is difficult to pronounce Spanish words.
=> I wish it were not difficult to pronounce Spanish words.
or: I wish I could pronounce Spanish words.
2. This is the first time my father has read this interesting book.
=> My father has never read this interesting book.
3. A doctor takes care of sick people
=> A doctor looks after sick people.
4. Designers made different styles of jeans to match the 1960s
=> Different styles of jeans were made by designers to match the 1960s.