1. Whether a planet can support life depends on the size and brightness of its star, that is its ´sun´.
    一颗行星是否能够维持生命取决于它的恒星--即它的"太阳"--的大小和亮度。

2. Darkness is an attribute of night, as brightness is that of day.
    黑暗是夜晚的本质，而白昼的本质是光明。