Submitted on: 26 October 2000.
Revised on: 18 November 2000.
Accepted on: 17 December 2000.
___________________Educational Research for Policy and Practice
http://reply.papertrans.cn/1/81/8085/8085-22.png
http://reply.papertrans.cn/1/81/8085/8085-23.png
http://reply.papertrans.cn/1/81/8085/8085-24.png
http://reply.papertrans.cn/1/81/8085/8085-25.png
Submitted on: 23 May 2005.
Revised on: 17 September 2005.
Accepted on: 10 October 2005.
___________________Educational Research for Policy and Practice
Submitted on: 06 August 2005.
Revised on: 27 November 2005.
Accepted on: 25 January 2006.
___________________Educational Research for Policy and Practice
http://reply.papertrans.cn/1/81/8085/8085-28.png
http://reply.papertrans.cn/1/81/8085/8085-29.png
http://reply.papertrans.cn/1/81/8085/8085-30.png