If you don't think you can get help before night comes为什么comes不用coming

If you don't think you can get help before night comes为什么comes不用coming

night 是抽象名词
comes 是动词
主语 night 要接动词第三人单数 comes .
这是语法规定,
before night comes
的句型和
before darkness falls
before panic sets in
before rain comes
一样.