Lightning is: a. when warm and cold air collide b. an indication of a high salt content in the air c. an indication that the atmosphere is virtually dust free d. a discharge of static electricity

2/6 of be by to 2/6 is to 24/72 ?

Name the two rivers that run through the fertile crescent. how were the rivers both positive and negative to societies of the fertile crescent?

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed