This episode's headline: China: A Delicate Relationship; Troubled Neighbor; Line Item Veto. The guests include In Washington: HARRISON SALISBURY, Journalist; Sen. LOWELL WEICKER, Republican, Connecticut; Sen. MACK MATTINGLY, Republican, Georgia; In Detroit: MICHAEL OKSENBERG, University of Michigan; In Boston: DWIGHT PERKINS, Harvard University. Byline: In New York: ROBERT MacNEIL, Executive Editor; In Washington: JIM LEHRER, Associate Editor