1) I have already visited Gorky Park, but I haven't visited "Sokolniki" yet.
2) I have already travelled to Vladimir, but I haven't travelled to Sochi yet.
3) I have already seen tigers, but I haven't seen lions yet.
4) I have already been to Paris, but I haven't been to Madrid yet.
5) I've already travelled to Africa, but I haven't travelled to Asia yet.
6) I've already visited Maths lesson, but I haven't visited English lesson.
7) I've already seen lakes, but I haven't seen seas yet.
8) I've already been to Moscow, but I haven't been to St Petersburg yet.
9) I've already seen red flowers, but I haven't seen yellow flowers yet.
10) I've already visited Poland, but I haven't visited Portugal.