下列化肥中，属于钾肥的是[ ]

A．KCl

B．NH₄NO₃

C．NH₄Cl

D．Ca(H₂PO₄)₂

野营时，小红携带的手电筒不发光了，请你帮助找出手电筒不发光的三种可能原因。

①                                                                                                     ；

②                                                                                                     ；

③                                                                                                     。