根据基本形态将细菌分为（）。
A、球菌、棒状杆菌和螺旋体
B、双球菌、链球菌和葡萄球菌
C、支原体、螺旋体和放线菌
D、球菌、杆菌和螺旋菌
参考答案：D
下列哪种疝不属于嵌顿疝（）
A.Richter疝
B.Littre疝
C.滑疝
D.逆行性嵌顿疝
E.直疝
Now the air in our city is ______ than it used to be. Something must be done to stop it. [ ]
A. very good
B. much better
C. rather bad
D. even worse
