⒈

G1G2(1?G4G5)C(S)? R(S)1?G4G5?G2G5?G1G2H?G4G5G1G2H⒉Unstable

415414⒌S: c(t)?1?e?t?e?4t, c(t)?t??e?t?e?4t; KP?? 、KV?and

3343125Ka?0, eSS?2.5

⒍S: ① this system is stable; ② unstable; ③ 0?K?1 unstable, K?1

critically stable, K?1 stable.