http://samueleresca.net/2015/03/the-difference-between-iqueryable-and-ienumerable/

IQueryablevsIEnumerable\enumerableTake.cs

public static IEnumerable Take(this IEnumerable source, int count)
        {
            if (source == null) throw Error.ArgumentNull("source");
            return TakeIterator(source, count);
        }

        static IEnumerable TakeIterator(IEnumerable source, int count)
        {
            if (count > 0)
            {
                foreach (TSource element in source)
                {
                    yield return element;
                    if (--count == 0) break;
                }
            }
        }