已若不等式t2-2at+1≥sinx对一切x∈[-π，π]及a∈[-1，1]都成立，则t的取值范围是______．
函数sinx在[-π，π]最大值是1，，
∴1≤t2-2at+1，
当t=0时显然成立
当t≠0时，则t2-2at≥0成立，又a∈[-1，1]
令r（a）=-2ta+t2，a∈[-1，1]
当t＞0时，r（a）是减函数，故令r（1）≥0，解得t≥2
当t＜0时，r（a）是增函数，故令r（-1）≥0，解得t≤-2
综上知，t≥2或t≤-2或t=0
故答案为：t≥2或t≤-2或t=0．
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| The two teachers were sitting in the teachers' room. For a moment there was _1 . Then one of them,Miss Smith, said, "I'm afraid I'd have to _2_ him." "Now, Alice," said her friend Mrs. Black, "is he such a terrible student?" "That's just the _3 ." the other woman replied. "Mike is my best student. The problem is that he's now so lazy that he never gets his 4 done. He hasn't handed me_5 of his homework for three weeks and I'd be surprised_6 he did now." _7 before had Mrs. Black seen Miss Smith look so unhappy. "Have you 8 with him about it?" she asked. "Why should I? He knows he has to prepare his lessons and do his homework. I _9 that clear the first day for class. When the course started he did so 10 considered asking the _11 to give him a scholarship . But now he even 12 in class! I've never seen such a _13_ in a student! "You should have _14 with him. Give him a chance to tell his side of the story." Miss Smith spoke to Mike and 15_ all about it. He was studying all day and 16 most of the night in a factory to pay for his education. Of course he was tired in the _17 and sometimes could hardly keep 18 . Miss Smith soon arranged for him to have a _19_ and he was able to give up his _20 and concentrate on his studies, | |||
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