在旋毛虫病流行中起重要作用的传染源是
A.蛇
B.狼
C.旋毛虫病带虫者
D.旋毛虫病病人
E.猪
参考答案:E
A great many teenagers became ________ playing computer games, wasting their precious time. [ ]
A. accustomed to
B. addicted to
C. used to
D. due to
下列钢号中,()是锅炉用钢。
A.16MnR
B.20
C.20g
D.A3F