Which of the following best explains the practice of placing indigenous children in boarding schools in the late nineteenth and early twentieth centuries?

Can someone list any possible solutions to air pollution ?

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4

The covers all of earth like a thin shell,but it is not a solid sheet of material.it is broken up into several large sections and many smaller ones. fill in the blank.