Rú / guǒ / méi / yǒu / míng / què / de / cān / kǎo / xì / hěn / nán / pàn / duàn / wù / tǐ / shì / fǒu / zài / yí / dòng

如果没有明确的参考系，很难判断物体是否在移动。

Without a clear frame of reference, it is difficult to determine whether an object is moving.