The Go$-$Back$-$N sliding window protocol with a window size of $4$ frames is used in

the following questions. The retransmission timer is set to t time units. Events for a sender and

a receiver are given in the tables below. Complete the tables with the appropriate responses. The

scenarios for the sender and receiver are not related.

events need to happen, indicate NONE, or if multiple events need to happen, list them in order.