Ответ:
1.Have they arrived already?
2. Lucy has run 2000 metres today.
3.’ve been cleaning all morning – I’m fed up!
4.How long have you known Simon?
5. I’ve been drinking more water lately, and I feel better.
6.Sorry about the mess! I’ve been baking.
7.How many times have you taken this exam?
8. He has eaten six bars of chocolate today!
9.Julie has cooked dinner. Let’s go and eat!
10.The students have finished their exams. They’re very happy.