"You look fat. What do you like to eat?"

That was the first jarring question one of his new Chinese high school students directed to American Peter Twomey when he reached the Jingshan Country School in northern Beijing.Despite its stark appearance, Jingshan is a boarding school for Chinese children from elite homes. It sits in quiet isolation on flat terrain in northern China. Despite its young age of two years, the school is dirty and plaster falls everywhere in the shabby interior.

The classroom is cold and barren. Twomey passes out American trinkets to the students, then they pepper him with additional questions. "Do you like the NBA? Do you know Michael Jordan? Do you like China?"

His impossible dream has come true. In the summer of 1996, Twomey, a history teacher in a large high school in Brockton, Mass., signed on for a three-week, free institute on China offered at Harvard University.

"My eyes bulged," Twomey said, "because I've always been interested in China." Each day he was intellectually stimulated as he listened to lecturers on Chinese history, society and culture.

Next, he contacted key people in the Newton, Mass., school system, to learn about their China exchange program. Surprisingly, Newton invited Twomey to be one of two teachers to go to China representing their city, and Brockton High granted him a four-month leave.

Following a six-month intensive study of the Chinese language, the 50-year-old Twomey felt enlightened but not fluent. He found Chinese to be "enormously challenging, simply because it is not related in any sense to a Western-based language."

Just as the Chinese send students and teachers to Newton, the Americans send five Newton students, plus two teachers, to spend February to June in Beijing.

The major fear of Chinese officials is that students visiting America will defect. In exchange programs, the rate of Chinese defection is more than 50 percent. But since the Newton project was organized in 1985, they have never had a defection.

Twomey preferred a quiet, non-smoking, non-English-speaking host family. "As long as I was jumping into the pool, I decided to choose the 12-foot end. The mother and father did not speak a word of English. Zhu Jiang was my 16-year-old `Chinese son,' who was very quiet and very polite. He translated for me."

In so doing, Zhu Jiang improved his own English, learning vocabulary and sentence construction as well as colloquialisms and slang.

The Zhus' middle-class family dwelling in northern Beijing is a three-room apartment in a rather bland 17-story apartment building.

The apartment has two large rooms and one small room, modest by American standards, "an itty bitty kitchen" and a small bathroom with a Western toilet.

In most places, Twomey said, "The standard toilet is a hole in the ground, and you squat."

Because only 5 percent of the 11 million people in China have automobiles, the predominant mode of transportation is bicycle.

Every morning Twomey pedaled 45 minutes to school in heavy Beijing traffic. Beijing is flat, but bikers stop at intersections, with thousands of other bicyclists.

"The congestion is very orderly," Twomey said, "because the Chinese follow rules more closely than we do."

Twomey's enthusiasm for China is palpable. "Every day my eyes were constantly opened. Even if I was dead tired, I was saucer-eyed, because everything was so new, so original, so astounding."

By the time Chinese students are seniors in high school, Twomey says, they speak splendid English, and all his students were unfailingly polite and cooperative.

"I didn't see anyone being mean to anyone else. In an American school, you might see someone being roughed up in the corridor. Not in China."

He also never saw a Chinese student ridiculing another student. He never observed a student who didn't have his homework prepared. "The students went home at night and spent a minimum of five to seven hours doing homework."

According to Twomey, they completed their assignments "because it was expected." Twomey said to his adopted son, Zhu Jiang, " `Does anyone ever refuse to do it?' He gave me a blank look, as if to say, `What are you talking about? Of course not!' "

It has something to do with the totalitarian state.

In China, high school students do not date, and boys and girls do not interact. Girls dress modestly, and promiscuity is nonexistent.

"I never saw men staring at women the way you see a man ogle a woman in the United States," Twomey said. "There are no unwed mothers. It would be an impossible situation. There is no apartment to live in. They would have dishonored their families."

The five American students enjoyed their host families, and each learned Chinese more quickly than their American teachers.

The chances are, Twomey said, that "no one is going to get mugged. I felt very comfortable taking buses and walking around late at night. I never saw a drunk on the street."

However, he was bothered by other problems, such as air pollution. "The fuel they burn is coal, and they can't afford to import oil. The air is black - incredibly filthy. The Chinese have more lung disease than most other people. But if you engage them in conversation about it, they say it is the price they must pay for industrialization."

Twomey retains warm feelings for his host family. "A bond grew between us. The father (Zhu Sheng Ping) and I would sit together in the evening for a language lesson. He would do the Chinese, I would repeat the words after him, and we would roar with laughter at our own clumsiness. His English was appalling, and my Chinese was beyond ghastly."

In Twomey's opinion, China will gain prestige if it combines its current economic advances with political progress. If it could im-ple-ment a free exchange of ideas without causing the society to implode, "the 21st century could be China's."

That's why Twomey is sold on educational exchange. "I come back bullish on China, loving the people and the country, wanting them to integrate themselves into the world community. I hope they can do it. They deserve it. There is genius all over China."

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ADDITIONAL INFORMATION

- High school students in China always do their homework, and they spend 5-7 hours a night doing it.

- They have extraordinary language skills. By the time they are seniors, they speak fluent English.

- Students stand when the teacher enters the classrom. They are unfailingly polite and cooperative. There are virtually no discipline problems at all.

- They never ridicule each other.

- They wear school uniform sweat suits to school.

- Puritanical standards predominate. Students don't date. In fact, boys and girls do not interact at all in high school.