Answer:
1) Jake and Sarax are skateboarding.(skate)
Jack and Sarax aren't skateboarding.They're skating .
2) Those dogs are fighting .(play)
Those dogs aren't fighting .Those are playing .
3) The bus is arriving.(leave)
The bus isn't arriving.It's leaving.
4)My uncle is playing football .(watch)My uncle isn't playing football.He's watching.
5) My aunt is doing aerobics.(dance) My aunt isn't doing aerobics.She's dancing.
6) I'm playing a game on my phone (write an email)I'm not playing a game on my phone.I'm writing an email.