【評論主題】21.二進位數 10100011(2) 作算術位移（arithmetic shift）向右移一位元（bit）後，試問所得結果為何？(A)01000110(2)(B)01010001(2)(C)1101
【評論內容】
算術位移運算
2 補數★★★★：...
【評論主題】20.設 x、y 為二元變數，x’, y’為其補數形式，⊕表 XOR 運算。若 A = (x ⊕ y) ⊕ y’，則 A 為下列何者？(A)1(B)0(C)x(D)x’
【評論內容】
A = (x ⊕ y) ⊕ y’
A = (xy'+x'y) ⊕ y’
(把(xy'+x'y)當作一個新的變數z來看 z⊕ y'=zy'+z'y 較易理解)
A =(xy'+x'y)'y'+ (xy'+x'y)y'' (展開後，可想成zy'+z'y)
A=[(xy')'(x'y)']y'+xy'y+x'yy ( 利用(xy)'=x'+y' ;(x+y)'=x'y'化簡)(yy'=0;yy=y)
A=[(x'+y)(x+y')]y'+x'y
A=[xx'+x'y'+xy+yy']y'+x'y (xx'=0)
A=[x'y'+xy]y'+x'y
A=x'y'y'+xyy'+x'y
A=x'y'+x'y
A=x'(y'+y) (y'+y=1)
A=x'
【評論主題】20.設 x、y 為二元變數，x’, y’為其補數形式，⊕表 XOR 運算。若 A = (x ⊕ y) ⊕ y’，則 A 為下列何者？(A)1(B)0(C)x(D)x’
【評論內容】
A = (x ⊕ y) ⊕ y’
A = (xy'+x'y) ⊕ y’
(把(xy'+x'y)當作一個新的變數z來看 z⊕ y'=zy'+z'y 較易理解)
A =(xy'+x'y)'y'+ (xy'+x'y)y'' (展開後，可想成zy'+z'y)
A=[(xy')'(x'y)']y'+xy'y+x'yy ( 利用(xy)'=x'+y' ;(x+y)'=x'y'化簡)(yy'=0;yy=y)
A=[(x'+y)(x+y')]y'+x'y
A=[xx'+x'y'+xy+yy']y'+x'y (xx'=0)
A=[x'y'+xy]y'+x'y
A=x'y'y'+xyy'+x'y
A=x'y'+x'y
A=x'(y'+y) (y'+y=1)
A=x'