List<string> fruits =
    new List<string> { "apple", "passionfruit", "banana", "mango", 
                    "orange", "blueberry", "grape", "strawberry" };

IEnumerable<string> query = fruits.Where(fruit => fruit.Length < 6);

foreach (string fruit in query)
{
    Console.WriteLine(fruit);
}

//引入命名空间
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] strings = { "one", "two", null, "three" };

        Console.WriteLine("Before Where() is called.");
        IEnumerable<string> ieStrings = strings.Where(s => s.Length == 3);
        Console.WriteLine("After Where() is called.");

        foreach (string s in ieStrings) {
            Console.WriteLine("Processing " + s);
        }

    }
}

int[] numbers = { 0, 30, 20, 15, 90, 85, 40, 75 };

IEnumerable<int> query =
    numbers.Where((number, index) => number <= index * 10);

foreach (int number in query)
{
    Console.WriteLine(number);
}