By day, Kenneth Cox went to high school played football, ran track, and did all the other things American teen-agers did in the late 1930s.

At night, he and his girlfriend at the Shanghai American School in pre-Pearl Harbor China would head for high ground and watch the Japanese bomb Shanghai across the Wangpoo River from where they sat.

"At first it was a big lark -- we'd go out and watch the bombs go by if our parents didn't pull us down first," Cox reminisced yesterday, as he attended his 40-year class reunion of a school that no longer exists.

"But at the first light, you'd see all the dead Chinese. Then you started to realize what has happening. It wasn't a joke."

Cox, now a procurement officier at the University of California at Santa Barbara, traveled to Northern Virginia this weekend to join the reunion of the school's class of 1940, many of whom he hadn't seen in 40 years. After swapping stories at a string of festivities all weekend long. Cox joined more than 100 other SAS schoolmates yesterday at -- approprimately enough -- Alexandria's China Gate Restaurant.

The sumptuous spread of Chinese food, 7,400 miles away from the site of their alma mater was a world apart from the strife-torn era in Shanghai that Cox and his friends remember. They graduated during the period when Japan was invading China and Mao Tse-tung and Chiang Kai-shek were jockeying for control of the world's most populous nation.

"Sometimes it's hard to believe we were ever there," said one, wistuflly.

Most who attended the Georgian-style Shanghai American School were the sons and daughters of missionaries, businessmen, diplomats and military officers who served in China in the first half of the century. Surrounded by the turbulence of a nation going to war, many of the students struggled to maintain a purely all-American ambience in a school that sat in the midst of Shanghai's French quarter.

The result was an often unnerving contrast, they said, between a quiet high school like any in the United States and a city in which shootings, bombing and assassinations were commonplace.

"It may sound crazy, but it was just around us all the time, said Dorothea Brown Castro, who was among a trainload of American students who fled another school for SAS when Japanese bombs began falling too close for comfort. "We grew up. That was all you could do."

One of her earliest memories, said Castro, a California public employe, was of sitting in Chiang Kai-shek's lap as a child when the Nationalist leader and his troops stopped to rest at her parents' religous mission. "He showed me his watch, or something silly like that," she said.

High school boys at SAS who had tried to help Japanese seamen improve their English were shocked to hear the Japanese boasting of their intent to invade the United States.

"The thing that bothered us very much when we came back is that nobody would listen to us," said Jim Harnsberger, now a doctor in Hot Springs, Va. "They [the Japanese] were talking very openly about bombing Pearl Harbor, and even taking the West Coast. When they'd get a few beers, they'd corral you and say these things."

The SAS that most of its alumni knew is gone now closed by the Japanese in World War II, revived after the war and closed again when Shanghai fell to the Chinese communists in 1949.

Although the building itself is still standing, recent visitors report that it is surrounded by a high brick wall and patrolled by armed guards.

While most of the school's alumni expressed intense interest in the country that shaped much of their childhood, many were reluctant to consider making the trek back to see how the communist revolution has changed the city they once knew so well.

"I have real mixed feelings about going back," said Agnes Masmith Johnston, an Alexandria housewife, about the city she considers her "memory Mecca."

"It's like any place you grow up. It just isn't the same. You can't go home again."