（1）forget doing (2)regret to do (3)regret doing (4)cease to

（1）forget doing (2)regret to do (3)regret doing (4)cease to do (5)cease doing (6)afriad to do (7)afraid doing (8)insterested to do (9)insterested doing (10)mean to do (11)mean doing (12)begin/start to do (13)begin/start doing