第三人称单数：mainlines 现在分词：mainlining 过去式：mainlined
1.主线,(铁路)干线,正线;〈美俚〉主血管;对主血管的海洛因注射
1.to do, eat, or take too much of something
2.to put illegal drugs into your blood using a needle
1.relating to the most common way of doing things or thinking about things
2.on a main line
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