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shall 应 指满足本规范必须遵从的强制性要求" h/ x. Q3 s5 W+ b5 X' h
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: G$ m: ^0 E, d" O0 J0 {
在否定证据当中不赞成某个措施但也不禁止
& q9 _! C3 @1 ~ C建议看一下:! o- |6 |4 r, P y
http://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay
& l2 a' G" Y2 X- A2 H, s Z E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" l4 v, }' [- }) S5 b0 S
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single-core cable: no preferred colour scheme;
! G0 g' h4 h) z8 A+ X* qtwo-core cable: no preferred colour scheme;
+ ]5 e- Q$ W4 x+ q; nthree-core cable: either green-and-yellow, blue, brown,3 e# M, ^" I, E* y6 I$ J% _- @
or brown, black, grey8 }* s8 Z9 ?4 f# y g8 Y$ n
four-core cable: either green-and-yellow, brown, black, grey,
7 [( H4 d7 |) m8 k% Nor blue, brown, black, grey
+ |8 D/ \' p" ~. O; g2 M2 Gfive-core cable: either green-and-yellow, blue, brown, black, grey,4 W. _* K, r; H
or blue, brown, black, grey, black.
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