Regular because all the sidesare the same
The Ming emperors made it their capital in 1421 and it remained China's capital till 1912 when the Manchu Empire fell and SunYat Sen turned China into a republic.
Answer:
a.expensive in some countries and
Radioactive isotopes decay and they released heat, more heat was generated and earth was hotter than it is today.
C. The inner core is known to be made mostly of nickel and iron. However, since there is an outer core (which is the original one that's made out of nickel and iron), your answer might be D. But if you put it the 'core' in general, the right answer should be C.
