命题“垂直于同一直线的两直线平行”的题设是( ),结论是( )。
两条直线都和同一条直线垂直;这两条直线平行
The poem _____ in tomorrow' s literature class is from a collection of classic works. [ ]
A. to be recited
B. to recite
C. be recited
D. being recited
下列物质不属于有毒物质的是
A.黄曲霉素
B.氯化钠
C.甲醛
D.二氧化硫