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$ f/ z! A2 \4 ?' ~ a$ zshall 应 指满足本规范必须遵从的强制性要求- g7 E/ |( I% C Z7 ?4 e
should 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: y$ s! O: [' ]( w7 K0 M9 O4 z3 ]
在否定证据当中不赞成某个措施但也不禁止+ ^/ q# E) c U$ I
建议看一下:; R6 |" S0 @% ~/ A6 S
http://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay
: k3 O5 v1 _6 {3 y* k) g) L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6 t7 Z# N: O- l) s
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single-core cable: no preferred colour scheme;
% P& F# H: x# V$ j( V* ^% c% |two-core cable: no preferred colour scheme;( U1 ]% O0 R L( b( _- @
three-core cable: either green-and-yellow, blue, brown,
+ Z- r4 H) e: ~8 w e9 ^or brown, black, grey# M9 k7 \0 K3 ^' u9 {( W7 {
four-core cable: either green-and-yellow, brown, black, grey,
; y u0 q D4 ^7 z, S9 yor blue, brown, black, grey
" |" |4 Y% r8 I. [5 Yfive-core cable: either green-and-yellow, blue, brown, black, grey,
3 ]8 {' K# n8 n" @' Z6 xor blue, brown, black, grey, black.! S$ V" j' B2 Z9 j
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