Shirley _____ a book about China last year, but I don’t know whether she has finished it

The audience _______ as they waited for the comedian to come on the stage.

Your watch is verynice. — .

依次填入下面一段文字横线处的语句，衔接最恰当的一组是心理学上有一种现象叫做过度理由效应。___________，___________，___________，___________，___________，___________。①心理学上的自我知觉理论对这种过度理由效应的解释是②简单地说，外在动机，例如金钱或物质奖励，会降低一个人工作表现的内部动机③而削弱了本来存在的内部动机④当外在动机出现时，人们会将注意更多地放在外在动机的奖励上⑤而减少了对活动本身的享受和对满足感的关心⑥这种效应将人们的动机转化为外部因素

Was it an accident or did David do it ________?