var a = 1;
var b = 2;
var test = function (first, second) {
  return first === a && second === b;
};
function callIt(fn) {
   var args=Array.prototype.slice.call(arguments,1);
   var result=fn.apply(null,args);--------------------------------args是数组,整体为一个参数，怎么能够传到first,second这两个参数呢？
   return result;
}