The relationship between the size of TCP congestion window cwnd and transmission round n is shown in the following figure: cwnd 1 2 4 4 8 8 16 32 33 34 35 36 37 3 38 39 n 1 2 3 4 5 6 7 8 8 9 9 10 11 12 13 cwnd 40 41 42 21 22 23 24 25 26 1 N 4 8 14 15 16 17 18 19 20 21 22 23 24 25 26 (1)Indicates the time interval of TCP in the slow start phase. (2)Indicates the time interval when TCP works in congestion avoidance phase. (3)After the 16th and 22nd rounds, does the sender detect the missing message segment by receiving three repeated confirmations or by timeout?and why? (4) In the first round, the 18th round and the 24th round, how big is the threshold ssthresh set? (5)In which round is the 70th segment sent? (20.09)