A:When's your birthday?
B:Who are you?
C:What are they?
补写句子
进价(元/台)
售价(元/台)
电饭煲
200
250
电压锅
160
①函数f(x)的图象一定关于某条直线对称;
②函数f(x)在R上是周期函数;
③函数f(x)的最大值为 14 ;
④对任意两个不相等的实数 x1,x2∈(0,32) ,都有 f(x1)−f(x2)x1−x2>110 成立.
其中所有真命题的序号是____.