下列抗生素中，哪些是来源于放线菌的
A．红霉素
B．四环素
C．链霉素
D．青霉素
E．两性霉素
参考答案：A, B, C, E
—Where is the shooting centre?
—It is about 50 kilometres ______ the city of Beijing.
A．in south of
B．south of
C．the south of
D．southern of
