下面都是口语表达：

Can I take you out for dinner?

Would you like to have dinner with me?

Can I buy you a dinner?

How about having dinner with me?

I would like to have dinner with you. When are you free?

Are you game for dinner with me? （这一句非常口语。）

Let's go out for dinner together. （这句话对不相熟的女性可能冒昧。）