1. The weakness of the root locus method compared with Frequency Analysis Method is
A. that it relies on the existence of the open-loop transfer function.
B. that it dose not rely on the existence of the open-loop transfer function.
C. that it is hard to draw the root locus when systems’ order is high.
2. Figure P1 shows a experimentally determined open-loop frequency response plot. Find one of the transfer functions listed below match it.
Fig. P1
A. 
.
.B. 
.
.C. 
.
.D. 
3. When one encircles a pole of F(s) once in the clockwise direction in the s plane, the origin of the F(s) plane is encircled_______ in the ___________direction.
A. once, clockwise.
B. twice, clockwise.
C.once, counterclockwise.
D.twice, counterclockwise.
4. which one is false in the following statements on the equation (1) to judge the stability of systems in Nquist Method.
Z=N+P (1)
A. Z=number of roots of 1+GH(s) in right-hand half plane.
B. Z=number of closed-loop poles of GH(s) in the right –hand half plane.
C. N=number of clockwise encirclements of the critical point.
5. When number of open-loop poles of GH(s) in the right –hand half plane is zero, and Nquist diagram is like P2. then the system is:
Fig.P2
A. stable.
B.unstable.
C.unclear.
6.Sketch the Nyquist diagram for the system described by the open-loop transfer function
.Which one is the Nyquist diagram of the system in the following diagrams when number of open-loop poles of GH(s) in the right –hand half plane P is assumed as 0?
Fig.P3 Fig.P4
A. Fig.P3.
B. Fig.P4.
C. none.
7.for the systems described by the Nyquist diagram shown in Fig.P5, estimate the gain margin and phase margin. Which one is truth?
Fig.P5
A. GM=∞, PM=30 o
B.GM=∞, PM=-30 o
C. GM=0, PM=-30 o
D. GM=0, PM=30 o
8. which statements on the following systems is truth.
A. 
.
.B. 
C. 
D. 
9. for the systems described by the Bode diagram shown in Fig.P6, estimate the gain margin and phase margin. Which one is truth?
A. GM=-11db, PM=-50 o
B. GM=11db, PM=-50 o
C. GM=-11db, PM=50 o
D. GM=11db, PM=50 o
10. When 
, 
_____ in a second-order system?
, _____ in a second-order system?A . 20.
B. 40.
C. 80.
D. 160.
11. When a system’s PM=38.6 and 
, 
_____?
, _____?A. 0.0657.
B. 0.657.
C. 6.57.
D. 0.957
12. According to the Nichols chart Fig.P7, which statements is False?
Fig.P7
A. GM=11,PM=32o.
B. gain crossover frequency is 10 rand/s.
C. the closed-loop bandwidth is 10rand/s.
D . the size of the closed-loop resonance peak is 5db
D . the size of the closed-loop resonance peak is 5db
正确的答案是：A、C、C、D、A、B、A、C、D、B、B、C
