#define LOWORD(l) ((WORD)(l))
#define HIWORD(l) ((WORD)(((DWORD)(l) >> 16) & 0xFFFF))


问题:
1,LOWORD(l)是什么意思?参数1又是什么意思?
2,(WORD)(l)和(DWORD)(l)又是什么意思?
3,(WORD)(l)>> 16是什么意思?
4,(((DWORD)(l) >> 16) & 0xFFFF))是什么意思?
5,((WORD)(((DWORD)(l) >> 16) & 0xFFFF))是什么意思?
6,#define HIWORD(l) ((WORD)(((DWORD)(l) >> 16) & 0xFFFF))整句又是怎么意思?