a simple but important tip

Which do you prefer, Diet Coke or Diet Pepsi?


What's the difference between these two questions?

1) Where do you live?

2) Which do you like better, New York or San Francisco?

1) is asking a fact. So, your answer should be simple. (ex. I live in Iowa.) However, 2) is asking your opinion, and you have to tell "why". So, the answer should be like:

I like New York better because there are many museums I would like to visit.

Of couse, real conversation doesn't always follow this rule. This simple tip will be helpful if you take any speaking test, though.