烟酸缺乏病描述，错误的是（）
A.饮食缺乏酪氨酸
B.有皮炎、腹泻和痴呆三联征
C.皮损多位于隐蔽部位
D.尿烟酸排泄量增加
参考答案：A, C, D
票据的延伸业务主要有（）。
A.贴现
B.鉴证
C.签发
D.承兑
I'd like to be a professional singer, but I don't think I've got ________.
A．a good voice enough
B．a good enough voice
C．a voice enough good
D．an enough good voice
