1) Yes, there are. There are some boys in my math class.
No, there aren't any boys in my math class.
2) Yes, everybody is ready for the test.
No, nobody is ready for the test.
3) Yes, some of us are Russian.
No, none of us is Russian.
4) Yes, there are. There are some good book stores in our town.
No, there aren't any good book stores there.
5) Yes, of course there is. There is something better.
No, there isn't. There isn't anything better. There is nothing better.