If scientists haven't been able to break the surface of our Earth, how do they know Earth has different layers?

What season is it in the southern hemisphere when it’s december? a) fall b) spring c) winter d) summer

Why have the countries of the region had difficulty establishing democratic governments in recent years? choose all answers that are correct b is also correct i need to know if theres any morecommunists have overtaken the countries of the caucasus region. the soviets established national borders in the region without considering the location of ethnic groups. fighting continues between armenia and azerbaijan over the nagorno-karabakh region. civil war between communists and islamic groups in tajikistan resulted in thousands of deaths and refugees are forced to flee. in a test!

Physical features of central america look at the map above which of the following is true