1. What do you think are the functions of rivers nowadays?
Rivers have various functions. In the UK, they were probably more important in the past because they were used for the transportation of goods, but I suppose this is still the case in many parts of the world. Rivers can be used as a source of renewable energy in the production of hydro-electric power, and they are also a source of fresh water for drinking and irrigation. Leisure activities are another function: fishing, canoeing, swimming, bathing... I'm sure there are many other things I haven't thought of.
2. What do you think of boats and ships as forms of transportation?
I'm not really a fan of boats and ships. If I'm going abroad, I like to get to my destination quickly, so I prefer travelling by plane. Of course, ships are vital for the transportation of oil and other heavy cargo.
3. Why do some people like to live near rivers, lakes or the sea?
Well, the view is probably a major factor; most people like to look out to sea, or across a river or lake. I'd much prefer to look out of my window onto a natural landscape than an apartment building in a city. Then there's the lifestyle: if you live by the sea, for example, you can lie on the beach, go for a swim, or do water sports like surfing or waterskiing. I definitely wouldn't mind living near a beach at some point in my life!
Note:
These answers are less formal than the essays I write for the writing test, and I say things like "probably" or "I suppose" when I'm not sure about the facts.