Mark ... (do) karate on Fridays. (-)
Mark does karate on Fridays. Mark doesn't do karate on Fridays.
My mum ... (sing) in the shower. (?)
My mum sings in the shower. Does mym mum sing in the shower?
We ... (watch) TV at the weekend. (-)
We watch TV at the weekend. We don't watch TV at the weekend.