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?1 ???a?b?c?????????????? (1) a15 , b 8 ,
c17
(2) a13 , b 15 , c14
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(1) a25 b20 c15 ____ _____
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(2) a13 b14 c15 ____ _____
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17
(No Transcript)
18
1.
B
A?????? B??????C?????? D??????
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????,???ABCD?,?B900,AB3,BC4,CD12,AD
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1? ??a,b,c??ABC???,? ?? a2b2c233810a24
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b
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