zuò / wéi / zhōng / jiān / rén / tā / bì / xū / yī / shǒu / tuō / liǎng / jiā / bù / néng / piān / tǎn / rèn / hé / yī / fāng

作为中间人，她必须一手托两家，不能偏袒任何一方。

As the intermediary, she had to serve both sides fairly and could not favor either one.