29．定义一种运算min{a,b}={a,(a⩽b)b,(a>b)min\{a,b\}=\left\{\begin{array}{l}a,(a\leqslant b)\\ b,(a>b)\end{array}\right.min{a,b}={a,(a⩽b)b,(a>b)．设f(x)=min{4+2x−x2f(x)=min\{4+2x-x^{2}f(x)=min{4+2x−x2，∣x−t∣}(t\vert x-t\vert \}(t∣x−t∣}(t为常数），且x∈[−3x\in [-3x∈[−3，3]3]3]，则使函数f(x)f(x)f(x)最大值为4的ttt值可以是((( )))