reasoning structure:
4500 agricultural implements at Colha--A
3000 Mayan pottery at Colha--B
A is similar to B; A isn't similar to any other culture else in the same period
conclusion: agricultural implements belong to Mayan culture
Q weaken
M 1. Mayan culture shares something common with other culture 2. The Mayan immigrated to Colha and adopted its predecessor's implements
Ceramic wear 陶瓷器
not mentioned in the article, out!