IList< T> （为了能够 Add（））可以写一个扩展方法： p>

If your collection type implements IList<T> (to be able to Add() to it) you could write an extension method:

public static Extensions
{
    public static TColl ToTypedCollection<TColl, T>(this IEnumerable ien)
        where TColl : IList<T>, new()
    {
        TColl collection = new TColl();

        foreach (var item in ien)
        {
            collection.Add((T) item);
        }

        return collection;
    }
}