I have swum lately
He has never been...
...sister has just gone...
His father has never cooked...
They have just gone...
The snow has just stopped
My friend has already finished...
I have met...
We have gathered...
She hasn't seen...
2) four envelopes
3) eight sheets
4) five stamps
5) nine letters
6) не могу понять что это на картинке (к тому же она не полностью на фотке), может быть билет?
Тогда two tickets
Чем отличается 3) от 5) тоже непонятно. Но надеюсь, чем-то вам помог.
12.1 I was ; You can't ; I had
12.2 The music was; The concert had just started; it began
12.3 I have just come;I had; I visited
12.4 I was shopping, I left; I put; I am
12.5 I have graduated; I have thought; I have been organising