I/
1. gender preference
2. organization
3. gradually
4. unlucky
II/
1. more happy => happier
2. a => the
3. must keep => must be kept
4. didn't write => has not written
III/
1. The problem is being studied by the scientists carefully.
2. I have not seen my uncle for two years.
3. Earth must be used to put out their campfires by the campers completely.
4. My watch is more expensive than her.
