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% K& W8 ?6 x; Z- H% H" jshall 应 指满足本规范必须遵从的强制性要求. l. ~0 V" ]$ K+ P3 k+ z+ B8 H7 i
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( ^! u$ {: r- i6 f! s* e( m
在否定证据当中不赞成某个措施但也不禁止
+ z& a8 l4 z* b* q7 q7 p建议看一下:
& c, U7 A9 [5 O' R+ e. ~http://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay
$ ?" S# t$ Z, t+ I" z+ E; D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5 G, _$ L. h" R* J# c
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single-core cable: no preferred colour scheme;0 U/ \" F) I% M/ v- a& E6 o6 C
two-core cable: no preferred colour scheme;
& e% A" W) F. f1 c" |three-core cable: either green-and-yellow, blue, brown,
! [) q% O6 Y2 y) r9 S+ ]or brown, black, grey5 B0 k1 }; }$ {' L" {$ t. N
four-core cable: either green-and-yellow, brown, black, grey,0 B+ f" K& X# w7 \4 d" K. e5 q3 F
or blue, brown, black, grey
1 H1 _' I+ E2 j/ [/ ?five-core cable: either green-and-yellow, blue, brown, black, grey,; x5 g5 n3 Y3 N5 |1 B% B! x
or blue, brown, black, grey, black. K! s, z$ P% Y r$ C
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