下列病变属于第一期梅毒的是（）
A.梅毒疹
B.梅毒树胶样肿
C.马鞍鼻
D.硬性下疳
E.麻痹性痴呆和脊髓痨
参考答案：D
—Why do many people keep dogs as pets?
—Because they are our ____ friends and they never desert their masters.
A．wise
B．brave
C．loyal
D．handsome
简述偏头痛的药物治疗。
