【单选题】History of the Solar CalendarA Solar Calendar is a way of measuring and recording periods of time.It takes for the Earth to revolve around the Sun. With the help of the solar calendar, we can predict ...
【单选题】History of the Solar CalendarA Solar Calendar is a way of measuring and recording periods of time.It takes for the Earth to revolve around the Sun. With the help of the solar calendar, we can predict ...
A.
The solar calendar was first developed by the Egyptians.
B.
The solar calendar coincides with the yearly flooding of the Nile River.
C.
In the Western World, the definition of the year is based on the Earth’s revolution around the Sun.
【单选题】Ir has not been common at Earth’s since the very beginning of the planet’s history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth’s core as the planet cool...
【简答题】一弹簧测力计下挂一圆柱体,将圆柱体从盛水的烧杯上方 离水面某一高度处缓慢下降,然后将圆柱体逐渐浸入水中.如 图是整个过程中弹簧测力计的示数 F 与圆柱体下降高度 h 变化关 系的图象.下列说法正确的是( ) A .当圆柱体刚好全部浸没时,下表面受到水的压强为 700pa B .圆柱体受到的重力是 10N C .圆柱体受到的最大浮力是 4N D .圆柱体的密度是 1.5 × 10 3 kg/m 3...