99色精品-9色在线-99色在线-99色视频 国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

單項(xiàng)選擇題

An occulting light is one in which ().

A.the period of darkness exceeds the period of light
B.there is only a partial eclipse of the light
C.the periods of light and darkness are equal
D.the period of light exceeds the period of darkness

微信掃碼免費(fèi)搜題