Answer:
1. D
2. A
3. Not sure, don't know what the images are.
4. Same as 3.
For number 17, the city with the highest polulation density is Tokyo. Most of Japan's people live there.
A green card doesn't have anything to do with citizenship, but is important if you want to stay here for a long time without committing to a citizenship. If you are ready, take the citizenship test. If not then get a visa or green card and take a course to become a citizen.
The river would most likely look old and nasty all the water would have been evaporated from the river
