Ответ:

1) I have been working out all afternoon but i have been only burning off 800 calories so far .

2) Tim Holmes has just broken the record, Ladies and gentlemen!

3)Can we stop now please,Mum?We have been planting flowers all day long!

4) I've been to Africa once and there's no other place like it.

5) Mary has been playing tennis for four years,but she has never made it to the finals.