mean synodic lunar month

例句：

1. 1. The moon is a natural satellite of the Earth, and it has a mean synodic lunar month of about 29.5 days.
   月亮是地球的一颗自然卫星，它的平均朔望月大约是29.5天。
2. 2. The lunar calendar is based on the mean synodic lunar month, which is about 29.5 days long.
   农历基于朔望月，大约29.5天长。
3. 3. The Chinese New Year falls on the first day of the lunar calendar, which is determined by the mean synodiclunar month.
   中国新年落在农历日历的第一日，这由朔望月决定。