Teachers and supporters take part in the Chicago Teachers' Union strike rally in downtown Chicago, the United States, on Oct. 17, 2019. Thousands of teachers and supporters rally on Thursday after Chicago Teachers' Union failed to make a deal with the municipal government on raising the teachers' salaries. (Photo by Joel Lerner/Xinhua)

Teachers march during the Chicago Teachers' Union strike rally in downtown Chicago, the United States, on Oct. 17, 2019. Thousands of teachers and supporters rally on Thursday after Chicago Teachers' Union failed to make a deal with the municipal government on raising the teachers' salaries. (Photo by Joel Lerner/Xinhua)

Teachers take part in the Chicago Teachers' Union strike rally in downtown Chicago, the United States, on Oct. 17, 2019. Thousands of teachers and supporters rally on Thursday after Chicago Teachers' Union failed to make a deal with the municipal government on raising the teachers' salaries. (Photo by Joel Lerner/Xinhua)

A teacher takes part in the Chicago Teachers' Union strike rally in downtown Chicago, the United States, on Oct. 17, 2019. Thousands of teachers and supporters rally on Thursday after Chicago Teachers' Union failed to make a deal with the municipal government on raising the teachers' salaries. (Photo by Joel Lerner/Xinhua)