servlet程序不能通过编译

package aaa.dt.web;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
public class servlettest extends HttpServlet
{
public void doGet(HttpServletRequset request,HttpServletResponse response)throws ServletException,IOException
{response.setContentType("text/html");
PrintWriter o=response.getWriter();
o.println("<html>");
o.println("<head><title>hhhhhh</title></head>");

o.println("<body>dsfhkdfh");
o.println("</body>");
o.println("</html>");
}
}
为什么不能编译成功 第9行找不到符号