根据下面一段对话内容，从下面的7个选项中选出能填入空白处的最佳选项。并将该选项前的字母填写在答题卡相应的位置上。其中有两项为多余选项。A：Excuse me．[16] _______B：Yes．You don’t know me，of course．I don’t teach here．I just give oral examinations here now and then．Don’t be nervous．A：Nervous?Who?Me?B：[17] _______I’m going to ask you a few questions．Then we are going to have a short con versation in English．Do you understand?A：Yes，of course I do．[18] _______B：After the examination，please，first of all，why are you learning English?A：Why am I learning English?B：Yes，I mean，what are you going to do with it?Are you going to be a teacher of Eng lish，or what else?A：[19] _______I really must ask you something first．B：Very well．If you insist，go ahead please!A：Would you like a cup of coffee?B：Pardon?What did you say?A：You see，I’m English．I’m one of the teachers here．I came to ask you if you would like a cup of coffee．B：[20] _______．And thank you so much!A：You must have wronged me．B：Oh!I’m so sorry about this．C：Please stop just a second．D：Are you Mr．Smith?E：But may I ask you something first?F：Is there anything I can do for you?G：Now，sit down please．