Why might one pursue a certification?

Any point on a country's production possibilities frontier represents a combination of two goods that an economy:

Communication comes in various forms. which of the following is considered an old form of communication? a) e-mail b) letter c) skype d) texting

Noah met an old friend at a coffee shop. he jotted down the friend's new phone number, but later that afternoon he could not find it or remember what he had done with it. a couple of days later, noah went back to the coffee shop, and while waiting in line, he suddenly remembered where he had put the phone number. this is an example of: