2 sentences for 主线 (zhǔ​xiàn)

1. 这部小说的情节主线非常清晰。

   zhè bù xiǎo​shuō de qíng​jié zhǔ​xiàn fēi​cháng qīng​xī.

   The main plotline of this novel is very clear.

   Source: Dong Chinese Dictionary

2. 这条高速公路的主线已经全线贯通。

   zhè tiáo gāo​sù gōng​lù de zhǔ​xiàn yǐ​jīng quán xiàn guàn​tōng.

   The main line of this highway has been fully connected.

   Source: Dong Chinese Dictionary