normal hydrocarbon

例句：

1. 1. The normal temperature for this region is 20 degrees Celsius.
   这个地区的正常温度是摄氏20度。
2. 2.The normal course of the disease is to progress slowly.
   这种疾病的正常进程是逐渐进展。
3. 3. The normalcy of life in the countryside is a welcome change from the urban hustle and bustle.
   乡村生活的正常状态是城市喧嚣的可贵转变。