238. If so, if not, B1 level with dialogue

How to use 'if so' and 'if not' in dialogue. A conditional clause to refer a previous direct or indirect 'yes-no' question where the answer might be ‘yes’. Do you think we could study more grammar? If so, could you give us more help with tenses? Is it possible to pay by credit card? If so, which card do you accept? Does Mrs Smith like wine? If so, does she prefer white or red? Could you tell me if she said anything about me? If so, what did she say? I was wondering if we could meet one ...