When did earth form a. during the precambrian supereon b. during the proterozoic eon c. during the jurassic period d. during the cenozoic era

the effect of the ming leaders banning ships with more than two masts was that there was no further construction of ships masts, because there was a surplus. ming emperors disallowed foreign exploration

1.) irish.

2.) settlers could obtain cheap land nearby

3.) steam engine

explanation:

to replace ineffective because   andrew jackson's spoil system was a deliberate policy after he became president to remove federal employees he considered to be political opponents and replace them with his own supporters.