下列关于中南半岛的地形、河流分布特点的正确选项是（ ）

①图示的结构包括3个神经元，含有3个突触

②如果B受刺激，C会兴奋；如果A，B同时受刺激，C不会兴奋，则A释放的是抑制性递质

③递质可与突触后膜的“受体”结合，“受体”的化学本质是蛋白质

④A，B一定是轴突，C可能是树突

某地建设了以沼气池为核心的生产自净农业生态系统，图1是该生态系统的结构模式图，图2是厌氧沼气池的结构模式图。请回答下列问题：

    Mrs Smith is my teacher．At school she____us English．Her English is very good so we all like her．She has got two daughters，Gina and Helen．They are____at our school．So I know some things about them Gina____English very well．Helen is good at music．She plays the____very well．She is in the Music____．There,she and our music teacher Ms White help students with the piano．