声门癌的主要特征是（）
A.喉异物感
B.声音嘶哑
C.吞咽困难
D.不易向颈淋巴结转移
E.咯血
参考答案：A, B, D
实际长度10米，在图纸上为1厘米，比例是1：100
A lot of research and studies have shown that Trench oil, taken out from kitchen waste, ______ the increase of cancers. [ ]
A. results from
B. attends to
C. contributes to
D. devotes to
attends to