输尿管结石多发生在()
A．输尿管上1/3段
B．输尿管中1/3段
C．输尿管下1/3段
D．输尿管跨髂血管处
E．肾盂输尿管连接处
参考答案：C
—Who is the man ______ by a group of students there?
—A professor _____ research on physics.
A．followed; did
B．following; did
C．followed; doing
D．following; doing
增毒的配伍关系是（）
A.相恶
B.相杀
C.相须
D.相反
E.单行
