最多发生双侧颈淋巴结转移的肿瘤是（）
A.舌癌
B.口底癌
C.颊癌
D.腭癌
E.上颌窦癌
参考答案：B
The number of smokers in China ________increased in recent years, and a number of them _________ the youth.
A．has; are
B．have; are
C．is; is
D．are; are
对庆大霉素的评价，下列哪点不正确：
A．对G-杆菌作用较强B．可用于耐青霉素的金葡菌感染C．耐药菌很少D．与羧苄西林合用可增强对铜绿假单胞菌的疗效E．具有耳毒性
