Ответ:

1 I have never tasted snails.

2 Paul has travelled to Las Vegas and San Francisco so far.

3 Karen has just returned from the supermarket.

4 Mr Brown hasn't seen his son since 2006.

5 I've read the lyrics to this song twice.

6 I haven't arranged a meeting with Mrs Donaldson before.

7 Mary hasn't called for four days.

8 My mum hasn't learnt how to drive yet.