Miss Li，___，is active all the time．Although she has not been well these days，her class is still full of laughter．
A．as you know B．all in all
C．to start with
A
【详解】
句意：李小姐，你知道的，她一直很活跃。虽然她现在身体不好，但她的课堂上仍然充满了笑声．
考查插入语。as you know如你所知；all in all总之；to start with作为开始；根据下文“Although she has not been well these days，her class is still full of laughter．”即使身体不好课堂也很充满笑声，由此推断，空格指“就如你知道的”，她一直都很活跃；故选A。