What belongs to you, but other people use it more than you?

According to the article in wiki answer, digital communication systems have more benefits than analog systems. they are faster and more flexible, and they offer better performance than analog communication

How did brunelleschi solve his problem with the dome of the florence cathedral? a. he created an outer support shell. b. he created many layers of support within the dome. c. he created external supports for the dome. d. all of the above

Need to answer this question on a discussion board post