Question

fill in the blank question surface currents are usually generated by. deep - ocean currents usually result from differences in between water masses.

Explanation:

1. For the first blank: Surface currents in the ocean are primarily driven by wind. Wind blowing across the ocean's surface creates friction, which moves the water and forms surface currents.
2. For the second blank: Deep - ocean currents are mainly caused by differences in water density. Water density is affected by temperature (colder water is denser) and salinity (more saline water is denser). When water masses have different densities, the denser water sinks and the less dense water rises, creating deep - ocean currents.

Answer:

First blank: wind
Second blank: density