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。
The garden _____ while they were away from here.
A．took good care of
B．was taken good care
C．was taken good care of
D．was taking good care of
血琼脂培养基属于（）
A.基础培养基
B.营养培养基
C.鉴别培养基
D.选择培养基
E.厌氧培养基
