What is used to determine when the communications channels are clear and when a device is free to transmit data

Larry sent an email to andy. andy didn't open larry's email but still understood what the message was. how did andy determine the message without opening the email?

Jackson is teaching the decimal number system. he wants his students to know how to expand numbers by powers of 10. which is the correct order in which digits are assigned values in the decimal number system?

Instruction active describing list features which statements accurately describe the features of word that are used to create lists? check all that apply. the tab key can be used to create a sublist. the enter key can be used to add an item to a list. the numbering feature allows for the use of letters in a list. the numbering feature can change the numbers to bullets in a list. the multilevel list feature provides options for different levels in a list.