The Lhasa dialect has tones, but Tibetan Pinyin does not indicate tone. As a result, Tibetan Pinyin cannot perfectly transcribe the sounds of the Lhasa dialect.
Mandarin
回到拉萨/回到了布达拉宫
回到拉薩/回到了布達拉宮
huí dào lā sà / huí dào le bù dá lā gōng
I returned to Lhasa / I returned to the Potala Palace