猪蛔虫最主要的致病作用是( )。
A.免疫损伤
B.继发感染
C.毒素作用
D.机械性损伤
E.夺取宿主营养
参考答案:E
As a member of one world, each of us has a role _____ to make the earth a better place.
A.playing
B.play
C.played
D.to play
小于1000立方米的储气罐与站内办公生活建筑的防火间距为()m。
A.20
B.18
C.15