Это задание на употребление Present Perfect (используется, когда важно подчеркнуть результат действия) и Present Perfect Continuous (используется, когда важна длительность действия)
3. I have been reading Tolstoy stories in the park for two hours.
4. I have read three stories
.
5. Granny has been knitting in the living room since morning.
6. Look! She has knitted a sweater for me.
7. My sister has been skating since childhood.
8. She has taken part in many competition so far.
9. Helen has been travelling round Europe for 3 weeks.
10. She has already visited 3 countries.