normal contact Riemannian manifold

例句：

1. 1.The temperature is normal for this time of year.
   这个季节的气温是正常的。
2. 2.The room was in a state of disarray after the storm.
   风暴过后，房间一片混乱。
3. 3.The food was normal and not overly spicy.
   食物正常，没有过于辛辣。