词类活用。    

①高者挂目长林梢                                         

②下者飘转沉塘坳                                         

③忍能对面为盗贼                                             

④俄顷风定云墨色                                             

⑤长夜沾湿何由彻                                        

采煤工作面两巷超前支护支柱初撑力不得低于（）。

A、50KN

B、60KN

C、90K

D、100KN