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, g- |! R, M& h8 E- w. Q& Bshall 应 指满足本规范必须遵从的强制性要求
. c% q8 Z2 I7 G1 Q, b0 a# p1 [ Hshould 应该 指在多个可能性当中,认为特别合适,但不排斥其它的可能性.或是优选一套措施,但不是要求.或是
( d5 K. ]% b9 G; c' P6 P在否定证据当中不赞成某个措施但也不禁止
# K" l: }" I0 x! W建议看一下:
7 y2 c! H7 F1 x+ |- b* l+ ~http://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay
# |' e0 u+ ?& l) g如果可以用别的颜色作为地线,那么,不排除让写标准的人承认,“棕、蓝”都可以用来作地线8 o0 P5 h: `( i5 K4 M l P
, U: a( [9 q9 R2 @, @" A
single-core cable: no preferred colour scheme;4 b9 S% a# i7 S, D/ S% V1 o4 Z
two-core cable: no preferred colour scheme;8 t* R# r( Q5 h0 p
three-core cable: either green-and-yellow, blue, brown,
& N- z& j e" s" v3 [- \or brown, black, grey
! C3 P9 E/ _( @" gfour-core cable: either green-and-yellow, brown, black, grey,
2 H! V! `3 T6 d: g* B; @or blue, brown, black, grey3 X' p6 C, H1 ?7 [0 c
five-core cable: either green-and-yellow, blue, brown, black, grey,/ a! C1 i' W2 }
or blue, brown, black, grey, black.7 L: i3 c# \% V, _# {+ z; N; |
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