Eric James Long, 36, a former gym teacher at a private school in Bethesda, was sentenced yesterday to 10 years in prison on a charge of child abuse.

The sentence was imposed by Montgomery County Circuit Court Judge James McAuliffe, who told Long's attorney that after December 1986 he would entertain a motion to reconsider the term.

Long pleaded guilty in May to one count of child abuse and one of a third-degree sex offense related to allegations that he had assaulted and abused boys aged 6 to 11 both at the French International School, where he taught, and in his Silver Spring neighborhood.

Long, who taught at the school from 1978 until his arrest in January, told the court he was sorry for the suffering and pain he caused the boys, their families and his own family.

Judge McAuliffe sentenced him to the maximum term of 15 years on the child abuse charge and ordered him to serve 10 of those years in prison and five on probation. He sentenced him to a 10-year suspended sentence for the third-degree sex offense and five years on probation.

The conditions of the probation bar Long from engaging in any occupation that involves children and require him to continue treatment at the Johns Hopkins Sexual Disorders Clinic.

Long was convicted in 1972 of sexually assaulting a boy and again in 1980 of sexually molesting a boy whom he coached in soccer. He was not jailed after either of those convictions but was given three years' probation and ordered to undergo psychiatric treatment.