Technology. Is it part of our lives?

Cellphones

Look at your text on page 26What tense is the verb in each sentence in

italic? Present perfect

Is the action or situation in each sentence finished?

No

Which sentence focuses on a situation up to now?

Cellphones have been around

Present Perfect We use it to talk about actions or states

that began in the past and are continuing now.

Can you give me an

example?

Difference between simple past and present perfectDo not use the present perfect when you want to talk

about a finished time in the past like yesterday or three days ago. Use the past simple instead.

The present perfect is generally used when we are giving recent news, and there is a connection with the present. On the contrary, we use the simple past to give older information: we are only talking about the past.

He has failed his driving test again. (This is new information)

 He failed his exam two times last year (This is old information)  

I have been ill all the week. (There is a connection with the present)

I was very ill last summer. I had 'flu. (No connection with the present)

Let’s see if you understand the differencehttp://www.eflnet.com/grammar/presperf1.ph

p

http://esl.about.com/library/quiz/bl_pastorperfect1.htm?lastQuestion=0&answers=0&submit=Next+Question+%3E%3E&ccount=0

In present perfect we can use: since / forfor + period

A period is a duration of time, for example: 5 minutes, 2 weeks, 6 years. For means "from the

beginning of the period until the end of the period." For can be used with all tenses.

since + pointA point is a precise moment in time, for example: 9

o'clock, 1st January, Monday. Since means "from a point in the past until now." Since is normally used with perfect tenses.

fora period

(from start to end)>===<

sincea point

(up to now)x===>|

for 20 minutesfor three daysfor 6 monthsfor 4 years

for 2 centuriesfor a long time

for everetc

since 9amsince Mondaysince January

since 1997since 1500

since I left schoolsince the beginning of time

etc

Do we use since or for with these time expressions? Christmas

Last night

The last thirty minutes

2009

Three years

This evening

My last birthday

Let’s play in teams Thanksgiving

Three years

Last summer

30 years

The last twenty minutes

This afternoon

My last birthday

1989