我这里有几个API函数，都是在网上查不到的，所以对这几个函数都不是很了解，这里想请高手帮忙解释一下。主要是解释这几个函数都主要是有什么作用，每个函数的返回值是什么？括号内的每个参数又各自代表什么意思等等，越详细越好，因为我刚开始学API，一点很不起眼的知识可能都会对我有很大的帮助，谢谢了。
Public Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Public Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long
Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (lpvDest As Any, ByVal lpvSource As Long, ByVal cbCopy As Long)
Public Declare Function GetKeyNameText Lib "user32" Alias "GetKeyNameTextA" (ByVal lParam As Long, ByVal lpBuffer As String, ByVal nSize As Long) As Long