[1 of 2 Upper Elementary/ Intermediate Proficiencies] Some changes in the earth's surface are abrupt (such as earthquakes and volcanic eruptions, while other changes happen very slowly (such as uplift and wearing down of mountains).
(1 of 2 Upper Elementary/ Intermediate Proficiencies] Some changes in the earth's surface; are; abrupt) (other changes; happen very slowly; ) (other changes happen very slowly (such as uplift; wearing down; )
1 of 2 Upper Elementary/ Intermediate Proficiencies] Some changes in the earth's surface other changes other changes happen very slowly (such as uplift
are happen very slowly wearing down
abrupt