1 HAVE BEEN DISCUSSING the problem for hours , but has not solved it yet.
2 correct
3 Is it still raining? No, it HAS stopped.
4 John has WON the championship two times.
5 The boys have BEEN FISHING for 3 hours.
6 correct
7 correct
8 He has HATED oranges since his childhood.
9 They have TAKEN the dog for a walk.
10 correct