Metric Conversion : Stamp from Australia

The above is from a set of 4 stamps issued by Australia in 1973, for metric conversion process on Mass, Temperature, Length and Volume. I only have the above 3 stamps in my collection, the complete set should also include the following.

China stamp, #2001-3: Clowns in Beijing Opera

One of the roles of Bejing Opera is called Chou or 丑，which is Clown or Comedy Actor.

For more explanation of the roles, please check from page below:
http://www.chinapage.com/xwang/roles.html
http://en.wikipedia.org/wiki/Beijing_opera#Chou

The following set made up of six stamps:
Scott No: 3085-90
Serial number: 2001-3
Values in set: 6
Denomination: 6.80 yuan
Date of issue: 15 February 2001
Designer: Li Qingfa and Jiang Weijie
Size: 30*40 mm
Perforation: 12*11.5
Sheet composition: 20
Printing process: gravure
Printer: Beijing Postage Stamp Printing House

The stamps depict the different characters from different stories:-
SN:(6-1), Title: Tang Qin
SN:(6-2), Title: Liu Lihua
SN:(6-3), Title: Gao Lishi
SN:(6-4), Title: Jiang Gan
SN:(6-5), Title: Yang Xiangwu
SN:(6-6), Title: Shi Qian