语法总结
过去完成时交代先做好的准备
they had taken special precautions 表示在真正野餐前，这些准备早就做完了。
相似句：
- They had hidden the money before the police arrived.
- She had packed everything before dawn.
so that 表目的
so that no one should recognize them 表明乔装的明确目的。
相似句：
- He whispered so that no one should hear him.
- They left early so that they could avoid traffic.
too ... 的反讽效果
too perfect 这里不是单纯夸奖，而是“过头了，反而坏事了”。
相似句：
- The plan was too clever to work smoothly.
- His excuse was too detailed to sound natural.