13 ( )
A B
14
A B C D
15 E-R 3 3m:n E-R
A4 B5 C6 D7
16
A
B
C
D
17.
A.
B.
C.
D.
18 T A S
A T A A AS X
B T A A AS
X
C T A A AS X
D T A A A S X
19. T1T2 2 (
)
A. B.
C. D.
T1 T2
A=100
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