光度级
参考答案：
一种特定光谱型的恒星按照自身发光度进行分级。
— Haven't I told you that you should be home earlier?
— Yes, but I home earlier than I usually do. [ ]
A. was coming
B. will come
C. came
D. had come
森林病虫害防治实行（）的方针。
