教授出售他们的知识，工人出卖自己的劳动力，农民出售他们的农产品。

Professors sell their knowledge, workers sell their labor, farmers sell their produce.

youdao

教授出售他们的知识，工人出卖自己的劳动力，农民出售他们的农产品。

Professors sell their knowledge, workers sell their labor, farmers sell their produce.

youdao