例句與用法

1. Pulsating variables are stars that are continuously expanding and contracting and therefore show variations in brightness
   例如脈動變星就是恒星本身不斷膨脹收縮，造成光度亦出現相應的變化。
2. Pulsating variables vary periodically , but for some stars , there may be sudden changes in their brightness . such kinds of stars are called eruptive variables . they include
   ：脈動變星的光度會周期性地改變，但有一些恒星的光度會在毫無先兆下變得光芒萬丈，這種恒星包括新星和超新星皆統稱為爆發變星。