【简答题】Some parts of the earth are more likely to have earthquakes than other parts. This is usually true of 1) areas because there the thickness of rocks is not even. It is easy to understand why people are...
【简答题】阅读理解。 In ancient Egypt, the pharaoh (法老) treated the poor message runner like a prince when he arrived at the palace, if he brought good news. However, if the exhausted runner had the misfortune to br...
【单选题】The Huygens-Fresnel principle tells us to pretend that each point of a wavefront in a slit or aperture is a point source of light emitting a spherical wave. Is this true only for points inside the sli...