2Who Is Bill Gates?Bill Gates is one of the richest and most successful business executives in the world. Millions of people have used his computer programs for the past three decades.Bill Gates has always loved working with computers. In fact, he has programmed computers since his early teens.He has been the CEO of Microsoft Corporation since Since then, Bill Gates has written several books and has given billions of dollars to schools. For the last several years, he and his wife Melinda have donated a substanial amount of money to organizations working in global health.
3+ Form 1 form of have past participle The present perfect is formed with:form of have+past participleBill Gates has been the CEO since 1975.Many people have used Microsoft’s programs.
4Form 2 Past participles can be regular or irregular. The regular form of the past participle isbase form of verb + -d or -ed.Gates has always loved working with computers.
5irregular past participles. Form 3Past participles can be regular or irregular.There are manyirregular past participles.Gates has been the CEO since 1975.He and his wife have given lots of money to schools.
6Form 4Note these common irregular past participles.write – written give – given be – been see – seen read – read do – done
7Present PerfectUse the present perfect to talk about something that began in the past and continues into the present (and may continue into the future).Bill Gates has been CEO of Microsoft since 1975.since 1975.nowpastfuturehas been CEO1975
8has written several books Using Since 1Use the present perfect with since + point in time to show when something started.Bill Gates has written several books since 1975.since 1975.nowpastfuturehas written several books1975
9Using Since 2 Since can also introduce a time clause. time clause Gates has programmed computers since he was 13 years old.since he was 13 years old.nowpastfuturehas programmed computersage 13
10Practice 1 Maria was in the garden yesterday. (since 9 a.m.) Change the sentences to present perfect. Add the since phrase in parentheses and delete any past tense time phrases.Practice 1Example:Maria was in the garden yesterday. (since 9 a.m.)Maria has been in the garden since 9 a.m.1. Bill Gates wrote many s yesterday. (since 1975)Bill Gates has written many s since 1975.They have given a lot of books to schools since 1990.2. They gave a lot of books to schools last year. (since 1990)I have seen many friends since I came home.3. I saw many friends last weekend. (since I came home)My sister has read many articles since last August.4. My sister read many articles last night. (since last August)5. My friend worked at a pizza place a year ago. (since 2003)My friend has worked at a pizza place since 2003.
11Using ForUse for + length of time to show how long something has lasted.Millions of people have used Gates’s software for the last three decades.for the last three decades.nowfor three decadespastfuturehave used Gates’s software
12Since and For five o’clock ten minutes yesterday two days last summer Note the difference between since and for .since + point in timefor + length of timefive o’clockyesterdaylast summer1996he was a childten minutestwo daysthree decadesmany yearsa long time
13Practice 2Complete the sentences with since or for.Example:Bill Gates has been married to Melinda French Gates ___________ 1994.since1. Computers have been used in schools __________ more than a decade.for2. I have had a computer in my office __________ the mid-1990s.since3. Many students have worked with computers __________ many years.for4. My computer hasn’t given me any problems __________ last year.since