Thank you very much Brian!

Hi Aline, The "perfect" tense in English has a subtle semantic difference from the regular past tense. Both are "past" tenses, and both mean that the event happened sometime in the past. The two sentences I worked at that restaurant and I've worked at that restaurant could both refer to the same time period. So it's a little confusing about when to use the perfect tense (with "have...ed") and when to use the simple past. The difference comes with the issue of *relevance.* The perfect tense with "have" somehow connects the past event to the present, and says, "Look at this past event! It's connected to what's happening now!" whereas the simple past can mean the opposite ("This isn't important anymore.") For example, at a job interview at a restaurant, you might say "I've worked at two restaurants before," to make your past experience connect to the present moment. It says, "Look! I have experience working in restaurants because I've done it before." The same person, at a different job interview (for a computer programming position), might answer this question a little differently: 1: "What did you do after college?" 2: "I worked at two restaurants." The working at the restaurants isn't relevant to the current job, so the speaker uses the simple past instead. The subtle shades of meaning between the perfect tense and the simple past can sometimes affect politeness. A teenager who wants to go out with his friends politely says to his mom, "Hey mom, can I go out with my friends? I've done my homework." By connecting the past event of doing his homework to his mother's present desire for him to do well in school, he is being amicable and polite. A more rude teenager who is watching TV: Mom: "Turn off the television and do your homework." Teenager: "Whatever Mom. I did my homework already." This implies that the doing of the homework is irrelevant and unimportant to the present situation.

Amazing, thank you very much Cate!