公共场所的卫生特点是()
A.人群密集,流动性大
B.容易造成污染
C.设备及人群重复利用率高,易污染
D.健康与非健康混杂,容易造成疾病传播
E.以上答案均正确
参考答案:E
A student at a Nevada middle school opened fire on campus, wounding two l2-year-old boys and__________ a math teacher.
A.kill
B.killing
C.killed
D.to kill
设备检修时,空气置换氮气指标是多少?