A:①②
B:①④
C:②③
D:③④
He looks sleepy. He must ____ last night, writing the essay.
子贡问政。子曰:足食,足兵(军备),民信之矣。子贡曰:必不得已而去,于斯三者何先?曰:去兵。子贡曰:必不得已而去,于斯二者何先?曰:去食。自古皆有死,民无信不立。这给我们的启示是( )