What are the names of the 4 main air masses?

While most people who lived in ancient egypt and the middle east avoided settling in nearby deserts, those regions protected them from their enemies. why do you think this was true?

The meseta in spain is a a. navigable river b. castle c. coastal plain d.plateau

Effective charts and graphs include all of the following except 1. simple, meaningful, attractive design 2. accurate information 3.at least five different colors 5.clear presentation of information