How do geologists study direct evidence of Earth’s interior?

Which continents lie only in the northern hemisphere

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

The declining axolotl population in mexico city is an example of in overcrowded cities. a. the surpassing of support capacity b. changes to natural environments and native species c. the lack of safe homes and tenured spaces d. the effects of a growing urban heat island