氯霉素最严重的不良反应是
A．消化道反应
B．骨髓抑制
C．二重感染
D．过敏反应
E．以上都不是
参考答案：B
Plastic bags and boxes________ "white pollution" are attracting more and more people's attention. [ ]
A. are known as
B. are known for
C. known as
D. known for
