久久国产欧美日韩精品,日韩国产精品久久久久久亚洲,99视频精品全部免费免费,91精品国产综合久久走光

感覺上我們好像已從天底走到了天頂.It felt as if we had traveled from nadir to zenith.天底天球上,在觀測者垂直向下的一點, 與天頂完全相對.A point on the celestial sphere directly below the observer, diametrically opposite the zenith....

“天底”的拼音為：tiān dǐ...

“天底”的英語可以翻譯為：nadir ...