hé / dào / tài / zhǎi / bó / zi / bù / néng / dú / zì / tōng / guò / zhǐ / néng / yóu / tuō / chuán / qiān / yǐn

河道太窄，驳子不能独自通过，只能由拖船牵引。

The waterway is too narrow for the barge to pass on its own, so it has to be pulled by a tugboat.