题目内容：
根据中文提示，将对话中缺少的内容写在线上。这些句子必须符合英语表达习惯。打句号的地方，用陈述句，打问号的地方，用疑问句。 提示：Michael突然牙痛，于是到药房买药。药剂师为他检查后推荐了一种药，要他记住每四小时服一粒(pill)。同时叮嘱他如果两天后不见好转的话，一定要去医院。
Pharmacist: Good morning．What can I do for you?
Michael: 51 ．What medicine do you think I should take?
Pharmacist: Let me have a look at your teeth, please, …Oh, it’s nothing serious．You can try this．It’s quite effective．
Michael: 52 ?
Pharmacist: It costs only $8．99 a bottle．
Michael: OK．One bottle, please．
Pharmacist: Remember to 53 ．
Michael: Sure．I will．
Pharmacist: 54 , you’d better go and see a doctor．
Michael: OK．Thank you for your advice．And here is a 10 dollar bill．
Pharmacist: Thank you, sir． 55 ．$1．01．Hope you’ll be fine soon．Bye．
Michael: Bye．
请将正确答案填在第51处
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