The primary function(s) of an automatic sprinkler system is(are) to（）.

A.extinguish the fire which triggers it

B.limit the spread of fire and control the amount of heat produced

C.protect people in the areas which have sprinkler heads

D.alert the crew to the fire

柳宗元说，“仆之所拒，拒为师弟子之名，而不敢当其礼者也。若言道讲古穷文辞，有来问我者，吾岂尝嗔目闭口耶？苟去其名全其实，以其余易其不足，亦可交以为师矣！”教师的角色是（）。

A.授业、解惑者

B.朋友

C.合作者

D.传道者