normal age-class distribution

例句：

1. 1. The temperature isnormal for this time of year.
   这个季节的气温是正常的。
2. 2. She wears a normaloutfit for the occasion.
   她穿着一件适合场合的衣服。
3. 3. The normal distribution of resources isessential for sustainable development.
   资源的正常分布对于可持续发展至关重要。