表达式14: polygon left parenthesis, "A" , "B" , left parenthesis, "D" . "x" plus "B" . "x" , "D" . "y" , right parenthesis , "D" , right parenthesispolygonA,B,D.x+B.x,D.y,D
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表达式15: "M" Subscript, "b" , Baseline equals 1 half left parenthesis, "A" plus "C" , right parenthesisMb=12A+C
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表达式16: "M" Subscript, "a" , Baseline equals 1 half left parenthesis, "B" plus "C" , right parenthesisMa=12B+C
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表达式17: "C" Subscript, "p" , Baseline equals "B" plus "D"Cp=B+D
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表达式18: "M" equals "A" plus "C" minus "D"M=A+C−D
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表达式19: polygon left parenthesis, "A" , "M" Subscript, "b" , Baseline , "D" , right parenthesispolygonA,Mb,D
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表达式20: polygon left parenthesis, "M" Subscript, "b" , Baseline , "M" , "C" , right parenthesispolygonMb,M,C
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表达式21: polygon left parenthesis, "M" , "M" Subscript, "a" , Baseline , "C" , right parenthesispolygonM,Ma,C
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表达式22: polygon left parenthesis, "B" , "C" Subscript, "p" , Baseline , "M" Subscript, "a" , Baseline , right parenthesispolygonB,Cp,Ma
