语法总结
while doing 的伴随背景
while playing truant 表示“在逃学期间”，让主线更紧凑。
相似句：
- He lost his wallet while travelling abroad.
- She met him while studying in Paris.
过去完成时交代更早动作
the boat had travelled to Calais 表示他醒来之前船已到达。
相似句：
- The train had left before we reached the station.
- She had finished breakfast when I called.
not ... but ... 的路线反转
did not take him... but to Perpignan 突出旅程不断偏离原计划。
相似句：
- The bus went not to the village, but to the town.
- He wanted tea, not coffee.