Intersect可以用来查找两个集合之间的匹配，如下所示:

// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call Intersect extension method.
var intersect = array1.Intersect(array2);
// Write intersection to screen.
foreach (int value in intersect)
{
    Console.WriteLine(value); // Output: 2, 3
}

然而，我想实现的是相反的，我想从一个集合中列出从另一个集合中缺失的项目:

// Assign two arrays.
int[] array1 = { 1, 2, 3 };
int[] array2 = { 2, 3, 4 };
// Call "NonIntersect" extension method.
var intersect = array1.NonIntersect(array2); // I've made up the NonIntersect method
// Write intersection to screen.
foreach (int value in intersect)
{
    Console.WriteLine(value); // Output: 4
}