对人致病的链球菌主要是（）。
A.A群链球菌
B.B群链球菌
C.C群链球菌
D.D群链球菌
E.E群链球菌
参考答案：A
To make our city more beautiful, rubbish into the river. [ ]
A. needn't be thrown
B. mustn't be thrown
C. can't throw
D. may not throw
为什么要创建国家森林城市？
