若函数y=（sinx-a）2+1在sinx=1时取得最大值，在sinx=a时取得

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问题填空题

若函数y=（sinx-a）²+1在sinx=1时取得最大值，在sinx=a时取得最小值，则实数a的取值范围为 ______．

答案

sinx=a时取最小值

因为-1≤sinx≤1

所以-1≤a≤1

因为sinx=1时取最大值，所以当sinx=-1时y的值不比sinx=1时y的值大

（-1-a）²+1≤（1-a）²+1

1+2a+a²+1=1-2a+a²+1

a≤0

综合得：-1≤a≤0

故答案为：-1≤a≤0

单项选择题

脊髓灰质炎疫苗初种年龄（）。

A．出生后2～3天至2个月

B．2个月

C．3个月以上

D．8个月

E．1岁以上

补全对话，情景问答

根据对话内容，在空白处填写适当的话语（话语可能是一个句子，也可能是一个短语或一词)，使对话完整。

A: Look! Our classmate Li Lei is playing basketball there.

B: Yes. He likes it very much. He practices playing basketball every day.

A: But we students should concentrate more on our studies than games. Playing too much can get 1

of schoolwork.

B: 2 . We should spend more time on our studies. But being professional basketball player like Yao

Ming is his dream.

A: 3 .

B: He knows that. But he thinks if he works hard, he will have a chance of achieving his dreams.

A: Do his parents wish him to be a professional basketball player?

B: No. He 4 . He thinks teenagers should be allowed to decide to do something by themselves.

A: 5 I think we should talk with our parents and ask them for permission (允许) when we need to

make important decisions. we are still young!