未知题型 A solar calendar is a calendar based on the monthly cycles of the Moon"s phases (synodic months), in contrast to lunar calendars, whose annual cycles are based only directly on the leap year.

单项选择题 计算周转轮系对应的转化轮系的传动比公式iABH=（ωA-ωH）/(ωB-ωH)中，____。

未知题型 冰箱，存放食物不宜过满，这样冷空气对流，延长使用寿命节约电量（）