—________.My books are on the sofa.
A：Yes, it is
B：Yes, they are
C：No, it isn't
D：No, they aren't
①对任意实数x，都有x﹣x≤0；
②若x1≤x2，则x1≤x2；
③lg1+lg2+lg3+…+lg100=90；
④若函数f（x）= 2x1+2x ﹣ 12 ，则y=f（x）+f（﹣x）的值域为{﹣1，0}．
其中所有真命题的序号是____．
