Making an invitation:
1.how about going with us for a lunch?
2.would you like to join us?
3.I'd like to invite you to the party.
4.why do not come and join us for a dance?
5.i wonder if you would like to come around and have a meal sometime?
accepting an invitation:
1.I'd love to.
2.it's so nice of you,thanks a lot.
3.that's a good idea.
4.sure, that sounds great,thank you!
5.sure, thanks for asking me.
declining an invitation:
1.I'm afraid I've got a lot of things to do tonight,perhaps tomorrow evening?
2.I'm sorry i can't,but thank you anyway.
3.