题干
—All the isatis root（板蓝根） is sold out!
—People are crazy! experts say there is no use eating isatis root to prevent H7N9, some people still don't believe it.
A：Although
B：Unless
C：As a result
D：In order that
答案(点此获取答案解析）
A
的定义域是0，2，则函数
的定义域是（ ）