tramlines
[ˈtræmlaɪnz]
n.
（钢中夹杂在薄板表面上留下的）条痕，纵痕，（轧件在孔型中过充满造成的）耳线;
电车轨道( tramline的名词复数 );
例句:
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However, they are often described as "guidelines not tramlines".
来自BBC
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In fact, these apartments are so bijou you can fit four of them on to a tennis court and still have the tramlines to spare.
来自THETIMES
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Within the structure of the piece, he was held, as if the staves were tramlines and there was only one way to go.
来自NEWYORKER