41. D congratulate → celebratecongratulate的宾语必须是sb，结构：congratulate sb on doing sth；celebrate的宾语才是sth.42. C third → three 或 D weeks → week表示“每隔...”的结构为：every + 基数词 + 名词（复数）= every + 序数词 + 名词单数43. B are → is此句的主语根据句意为单数，所以谓语动词用三单is44. B how → what结构what to do next中，do缺少宾语，所以用代词what，而不能用副词how45. done → to
1.What do you usually do to celebrate your birthday?2.They both meet once every three weeks.3.All we have is her birthday cake，Let’s divide it.4.I don’t know what to do next.
未改之前是两句话，中间应该加连接词。要说别扭，这句话更别扭：The disputing parties may also jointly choose from among the members of the Maritime Arbitration Commission a sole arbitrator to form by himself
41-45 ADBAB 46-50 DDDAD正确的句子：41.What did you usually do to congratulate your birthday？42.They both meet once every third week.43.All we have is her birthday cake，Let’s di
