a) No, I'm not playing tennis now;
b) Maybe some friends of mine are doing an English test;
c) No, she isn't. She isn't singing any song;
d) I'm surfing on the net now;
e) Yes, I am.
Espero ter ajudado, mas lembre-se, essas são minhas respostas, use elas como base para construir as suas :)
a) are you playing tennis now?