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) v8 N8 z7 t5 [/ u1 W& j& v4 Kshall 应 指满足本规范必须遵从的强制性要求# x+ P0 O: f G0 U% Q
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& B3 Y* B% |' g) q' P
在否定证据当中不赞成某个措施但也不禁止3 N( T5 @* p# w+ P
建议看一下:: t( J, l1 U( ~+ _& L8 Z
http://bbs.angui.org/forum.php?m ... ghlight=shall%2Bmay
! a& s7 ~; {7 c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0 C* \% F# D3 \: O2 u
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single-core cable: no preferred colour scheme;
) x' {' T* ]6 M$ h- [6 ] b/ \two-core cable: no preferred colour scheme;
6 }- z5 W$ W% Q- g6 Pthree-core cable: either green-and-yellow, blue, brown,
% N m, G+ g& z8 g) xor brown, black, grey; f' l5 Y9 S& @
four-core cable: either green-and-yellow, brown, black, grey,* j- Y$ {7 M# ~ [; s$ h2 _
or blue, brown, black, grey6 b) [% u3 i7 y- i( L8 l w$ u
five-core cable: either green-and-yellow, blue, brown, black, grey,; k. a' ]) e8 {8 \. |" L
or blue, brown, black, grey, black.
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