Geologists can use waves to learn about Earth’s interior. P waves travel faster than S waves. S waves travel through solids only, which tells geologists that the core is liquid. Geologists call the outer, solid area of Earth the crust; the next layer is the . Finally, at the very center, is the core.

If the imperial dynasty had continued to rule china, it is most likely that a) the economy would have improved rather than weakened b) european nations would have gotten more of a foothold in china c) revolutionary groups would not have gained any power in the country d) communism would not have received support among the poor