IDLH环境应使用以下哪种呼吸防护用品()。
A.防毒面具
B.送风式长管呼吸器
C.正压式空气呼吸器
D.以上均不正确
参考答案:C
It is in their ability to speak ______ humans ______ from animals.
A.which; differ
B.that; different
C.which; different
D.that; differ
以牙槽骨水平吸收为主的牙周炎是()
A.复合性牙周炎
B.晚期成人牙周炎
C.青少年牙周炎
D.快速进展性牙周炎
E.牙周脓肿