public String DelSheet() {
	 sid=request.getParameter("sid");
		String op=request.getParameter("op");
			Long asid=Long.valueOf(request.getParameter("asid"));
			AnswersheetDAO adao=DAOFactory.getAnswersheetDAO();
			boolean ret=adao.delAnswersheet(asid);
			if(ret==true){
				//response.sendRedirect("../admin/ShowSheets.jsp?sid="+sid);
				return "success";
			}else{
				//response.sendRedirect("../admin/OpResult.jsp?op=DelSheet&ret=false");
				return "fail";
		}
	}