题干
His father __________ have a ball.
A：doesn't
B：don't
C：isn't
D：aren't
答案(点此获取答案解析）
A
His father __________ have a ball.
A：doesn't
B：don't
C：isn't
D：aren't
在区间
上是减函数，则
的最小值是（ ）
