−4, ,0, , , 2013, −(+5), +1.88, 0.010010001…, −2.33….
整数集合{__________________________ …}
非负数集合{______________________________…}
分数集合{_______________________________…}
无理数集合{ ____________________________…}.
, 3, , , 0.1010010001…, , 0, , , .