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shall 应 指满足本规范必须遵从的强制性要求7 z" s: j, F' v9 v
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
& M: t6 O, D' p. i/ m2 F+ Z3 |在否定证据当中不赞成某个措施但也不禁止2 [) Z5 h9 S% q1 H- P8 ^
建议看一下:
+ Q6 P5 l# h3 v0 V+ n# Ihttp://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay4 o$ r- C; D8 [2 a5 X1 K/ H
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; c5 c, U: ^8 j# {
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single-core cable: no preferred colour scheme;* Q, {9 M' E9 K
two-core cable: no preferred colour scheme;
1 J) F9 E8 a5 x' C( Qthree-core cable: either green-and-yellow, blue, brown,
# H8 l. [# l( i' d4 x4 Bor brown, black, grey
# U) w3 B3 W, @) S: s; }0 rfour-core cable: either green-and-yellow, brown, black, grey,3 e3 E2 ]7 A+ r5 W$ R
or blue, brown, black, grey% I; b0 l h( e9 v
five-core cable: either green-and-yellow, blue, brown, black, grey,. B/ @. I$ M# {5 m: W; [
or blue, brown, black, grey, black.
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