感染通过血行蔓延（）
A.败血症
B.风湿热
C.支气管肺炎
D.咽后壁脓肿
E.胃肠炎
参考答案：A
—Excuse me. _______ is your pen pal from?
—He's from Australia. We have been pen friends for three years. [ ]
A. What
B. Who
C. Where
D. Why
渐开线上任意一点的法线必与基面（）。
A、相离
B、相切
C、相交
