Dear CAE Candidate,
You might know a little bit about the history of English - it was heavily influenced by other languages, especially old German, French, Latin, and Greek.
How does that affect you? Well, usually the word from French is more formal than the word from German, while words from Latin and Greek can be more suited to academic writing.
A well-known example are the adjectives kingly (Germanic), royal (French), and regal (Latin). Better to use 'kingly' in an informal letter, 'royal' in a formal letter, and 'regal' in an essay. See?
Also, have you ever noticed that the name of an animal is different from the name of its meat? That's because a thousand years ago, the poor farmers who took care of the animal (e.g. cow) couldn't afford to actually eat the meat (e.g. beef), and it was the rich French-speaking noblemen who ate and named the food.
Take a look:
Name of Animal (Anglo-Saxon) - Name of Meat (French)
- Cow - Beef
- Pig - Pork
- Chicken - Poultry (normally called 'chicken' these days)
- Sheep - Mutton
- Deer - Venison
There's a very useful Wikipedia entry on this topic - it might be worth spending ten minutes on it!
There's a good book about the history of the English language from a writer called Bill Bryson. I often recommend his books to my students because they're easy to read and interesting.
You can check out the current price on Amazon using this affiliate link: http://geni.us/Bryson
Let me know if you enjoy it!