如何選擇使用空畫刷

CDC *pDC = NULL;
 pDC=GetDC();
 CPen pen;
 pen.CreatePen(PS_SOLID,2,RGB(255,0,0));
 CPen* oldpen=pDC->SelectObject(&pen);

 pDC->SetBkMode(TRANSPARENT);
        //選擇空畫刷
 pDC->SelectStockObject(NULL_BRUSH);
 pDC->SetTextColor(RGB(255,0,0));

 CRect rc(20,20,120,120);
 pDC->Rectangle(&rc);
 pDC->SelectObject(oldpen); 

 ReleaseDC(pDC);