SQL Tree在特定级别查找anscestors

Say I have the following tree:

说我有以下树:

CREATE TABLE Tree(Id int, ParentId int, Name varchar(20), Level int)

INSERT INTO Tree(Id, ParentId, Name, Level)
SELECT 1, NULL, 'Bob', 0 UNION ALL 
SELECT 2, 1, 'John', 1 UNION ALL
SELECT 3, 1, 'Bill', 1 UNION ALL
SELECT 4, 3, 'Peter', 2 UNION ALL
SELECT 5, 4, 'Sarah', 3
CREA