人体细胞在生命活动中不断产生各种废物,其中尿素等废物主要的排泄途径是( )
A.汗腺分泌汗液
B.泌尿系统形成尿液
C.呼吸道形成痰
D.消化系统形成粪便
答案:B
---What a large and bright room ! Is it a classroom?
---No, It _____ the students’ reading-room.
A.refers to
B.stands for
C.is supposed to be
D.is meant for
本身用雷管引爆,又能引爆炸药的是()
A、导火索
B、导爆索
C、导爆管