One of the questions that comes up again and again in English classes is the difference in meaning between present perfect and present simple.
To show you how these work, take a look at this article (from The Independent - http://tinyurl.com/35p2ltb) about actress Lynn Redgrave, who died on Sunday:
Lynn Redgrave...who became a symbol of the 1960s for her free-thinking character in the film Georgy Girl has died of breast cancer aged 67.
Her son, Ben, and daughters, Kelly and Annabel, were with her when she died in Connecticut on Sunday. Yesterday, they released a statement mourning her loss. "Our beloved mother Lynn Rachel passed away peacefully after a seven-year journey with breast cancer," they said.
Why the difference? It all comes down to an idea called ASPECT - the rules and conditions which tell us why one verb is possible in a situation, and another isn't.
Perfect tenses are called "perfect" because you can "see" or understand the ENTIRE action perfectly - you know when it starts, you see the entire length of the action from when it begins to the time when you're speaking. In that sense, the idea of "perfect" is very close to the idea of time. You understand that the action (or state) starts in the past and continues to the time you're speaking; you're not missing or eliminating any time. The TIME is not finished (because it continues to "now") and the ACTION may not be finished.
That's why the introduction of the article says that Lynn Redgrave "has died". It's NEW news to YOU, the reader, so the time is not finished.
Simple tenses, in contrast, are simple because they don't have language that tells us that we need to use another tense. They're simple because they do not have complications or additional information that tells us we need another tense.
Take a look at the third paragraph of the obituary:
The news comes less than a month after the death of her older brother, Corin Redgrave, also an actor, who died of cancer on 6 April, and a year after her niece, the actress Natasha Richardson, died from head injuries sustained in a skiing accident.
In this case, the ACTIONS (died) are finished and the TIMES (6 April / last year) are finished. They are not connected to now, and they cannot happen again. In this case, PAST SIMPLE is the only option we can use.
So, if you're not sure which tense you need to use, think of these three questions:
a) Is there some kind of time language that connects the action in the past and the present, such as "since", "for", "ever" and "never?" If there isn't, use PAST SIMPLE.
b) Does the verb talk about a historical figure (Cervantes, Queen Elizabeth I, Mussolini), a time in the past (the Victorian Era, the Carlist Wars, the Great Depression), or someone who's dead (Antonio Vega, Errol Flynn, Agatha Christie)? Use PAST SIMPLE.
c) Do you see time language that uses words like "last" (last month/last class /last year?) Use PAST SIMPLE.
And if you're genuinely not sure, use PAST SIMPLE. More often than not, you'll be correct.