在各种化学性致癌物中致癌谱广，致癌力又强的是（）
A.烷化剂
B.亚硝胺类
C.霉菌毒素
D.芳香胺类
E.氨基偶氮类
参考答案：B
I’ve heard that we will set out _________ the morning of Dec 25th .
A．at
B．in
C．on
D．over
Which type of warranty is enacted if a service or product does not meet the level of quality specified in the contract ？（）
A．Implied warranty of merchantabilit
B．Implied warranty of specified qualit
C．Express warrant
D．None of the abov
