趺蹶、手指臂肿、转筋、阴狐疝、蛔虫病合篇的原因在于（）
A.病因相同
B.病机相似
C.不便归类
D.均属外科
参考答案：C
—I don't have any change with me. Will you pay the fare for me?
— ________ .
A． That's fine
B． Nothing serious
C． Never mind
D． No problem
（3x+2）（3x-2）=______．
