Yesterday we played football together. He doesn’t speak English every day. Do you always skate in the park?Look! She is singing a beautiful song now.Will you go for a walk with me tomorrow? They usually swim in the swimming pool.It was a difficult test yesterday.My family don’t like my new boyfriend, because he doesn’t like to play basketball. Tomorrow his friends will buy или are buying new bikes. Are we reading books now?
I'm going to watch TV. Are you going for a walk tomorrow? I am not going to play football at 6 o’clock. Yesterday we saw Ivan.
Ник играет в футбол в этот момент, поэтому он не может ответить на телефон (звонок).
Поскольку играет он в данные момент, это временное событие и оно происходит в момент другого действия, то должно быть использовано время:
Present Continious.
Т.е. имеем
b) is playing.
Nick is playing football at the moment, so he can't answer the phone.